ASTRONOMY
TECHNOLOGY TODAY Your Complete Guide to Astronomical Equipment
THE VIRTUAL OBSERVER PART 2 • PARKS ASTROLIGHT NEWTONIAN SCOPESTUFF EBONYSTAR LAMINATE ROUND-BEARING KIT ORION’S SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER
The Evolution of Intelligent Design A History of Starizona’s HyperStar Volume 2 • Issue 10 October 2008 $5.00 US
Contents Industry News
Cover Story Images -29 An 8-inch Celestron Schmidt Cassegrain telescope is shown with HyperStar lens system installed, carrying a Starlight Xpress CCD Camera. The new HyperStar III lens accommodates CCD chips of up to 27-mm diagonal, illuminating a huge field of view at incredibly fast speeds (f/2). It also features precision collimation and camera rotation adjustments, and can be installed in mere minutes. Raw data for the background two-frame mosaic of the M42 region was captured by Professor Greg Parker using the C11 equipped with his original HyperStar lens and was processed by Parker’s collaborator of long standing, Noel Carboni of Florida.
11 CARINA SOFTWARE Voyager 4.5 Now Available 12 ASTRO TRAC Offers Upgrades with the AstroTrac TT320X
In This Issue 8
Editor’s Note Subscription Renewals, Back Issues, Corrections, Who Writes This Stuff, Hurricanes and Friends in Low Places By Gary Parkerson
14 MEADE INSTRUMENTS Introduces mySKY Plus 15 NORTHEAST REGION OF THE ASTRONOMICAL LEAGUE Presents Stellafane Walter Scott Houston Award to Mike Mattei
29 The Evolution of Intelligent Design A History of Starizona’s HyperStar By Scott Tucker 35 Deep-Sky Imaging with Starizona’s HyperStar How the New Forest Observatory Re-Discovered the HyperStar By Greg Parker 41 The ScopeStuff EbonyStar Laminate Round-Bearing Kit An Easy Upgrade to Budget Dobs By Jason Scherff 49 The Virtual Observer Part 2 A New Breakthrough Technology for the Visual Observer By Roger Blake
55 The Orion Sirius EQ-G Mount and StarShoot AutoGuider Taking a Long Ride with the Sirius EQ-G and SSAG By Dave Snay 65 The Parks Astrolight Newtonian An Instant Classic By Erik Wilcox 68 Astro Tips, Tricks, and Novel Solutions Daisy, Daisy, Give Me the Altitude… By Rod Nabholz
16 CATSEYE COLLIMATION Adds New XLS TeleCat/TeleTube Lines and Online Procedures and Instruction Downloads
17 STARK LABS Releases Nebulosity 2.0 and PHP Guiding 1.9
Astronomy TECHNOLOGY TODAY
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Contributing Writers
Contents New Products 18 ASTRONOMY SHOPPE New Scope-Scout Bracket
Roger Blake is a retired nuclear engineer with a degree in physics from Drexel University in Philadelphia. He has been an amateur astronomer and astrophotographer for 30 plus years. Roger spent his early years in research, but later migrated into the nuclear power industry, responsible for the computer modeling and analysis of reactor physics behavior and thermal margins. He now applies his modeling skills to several astronomy related research and development projects, including the creation of the new Dark Sky Maps and the Virtual Observer. Rod Nabholz has been hooked on amateur astronomy since the first object viewed through his first scope, the Shoemaker Levy impacts on Jupiter. He views near his home in Independence, Iowa, where he lives with his understanding wife, Donna and his three children. His 13-inch reflector is home built, as is much of his equipment that he shares via his website www.homebuiltastronomy.com. He also enjoys wild bird photography and his images can be seen at www.wildsideiowa.com. When not under the stars, Rod is a Credit Manager for an energy company. Greg Parker is by day a Professor of Photonics at the University of Southampton U.K., researching Photonic Crystals, also called Semiconductors for Light. By night he runs his New Forest Observatory taking wide-field deep-sky images which he subsequently sends to Noel Carboni in Florida U.S.A. for expert processing. This highly successful International Internet Collaboration began in early 2005 and will result in their first joint publication, Star Vistas (Springer), in January 2009.
Jason Scherff is a Registered Polysomnographic Technologist at Yale University with over 10 years of experience in the sleep medicine field. In addition to practicing fatherhood, he can often be found photographing birds, or writing music. He is currently the president of Thames Amateur Astronomical Society in Southeastern CT.
David Snay is a retired software engineer living in central Massachusetts. He graduated from Worcester Polytechnic Institute and has been an astronomer and astrophotographer for more than 10 years. David currently pursues fine art photography, specializing in traditional black/white images.
Scott Tucker grew up in Michigan where one rare night the clouds finally parted and unveiled the stars. He works at Starizona where he writes educational guides for the Web, helps develop new products, shares his expertise on imaging and love of the night sky with the public, and even finds time to draw astronomical cartoons.
Erik Wilcox has been observing the sky for more than 20 years. In addition to being a longtime moderator on the popular astronomy forum at www.cloudynights.com, he recently started a new forum at www.starstuffforums.com. When he’s not viewing the sky, he sings and plays guitar in a rock band.
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19 STELLARVUE Introduces SV70ED Refractor
21 SCOPESTUFF New Stuff from Scopestuff 22 FLEMING ASTROPHOTOGRAPHY Astrophotography Tutoring Service 23 APM TELESCOPES High Brightness R-G-B 50 Micron Artificial Star and Deluxe Doublet ED Binocular
24 ORION TELESCOPES & BINOCULARS More New Products for the Fall 26 FARPOINT ASTRONOMICAL RESEARCH Introduces 2-inch Desiccant Caps
The Supporting
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ASTRONOMY
TECHNOLOGY TODAY
Volume 2 • Issue 10 October 2008 Publisher Stuart Parkerson
Managing Editor Gary Parkerson
Associate Editors Russ Besancon Karol Birchfield Jessica Parkerson
Art Director Lance Palmer
Staff Photographer Jim Osborne
Web Master Richard Harris
3825 Gilbert Drive Shreveport, Louisiana 71104 info@astronomytechnologytoday.com www.astronomytechnologytoday.com Astronomy Technology Today is published monthly by Parkerson Publishing, LLC. Bulk rate postage paid at Dallas, Texas, and additional mailing offices. ©2008 Parkerson Publishing, LLC, all rights reserved. No part of this publication or its Web site may be reproduced without written permission of Parkerson Publishing, LLC. Astronomy Technology Today assumes no responsibility for the content of the articles, advertisements, or messages reproduced therein, and makes no representation or warranty whatsoever as to the completeness, accuracy, currency, or adequacy of any facts, views, opinions, statements, and recommendations it reproduces. Reference to any product, process, publication, or service of any third party by trade name, trademark, manufacturer, or otherwise does not constitute or imply the endorsement or recommendation of Astronomy Technology Today. The publication welcomes and encourages contributions; however is not responsible for the return of manuscripts and photographs. The publication, at the sole discretion of the publisher, reserves the right to accept or reject any advertising or contributions. For more information contact the publisher at Astronomy Technology Today, 3825 Gilbert Drive, Shreveport, Louisiana 71104, or e-mail at info@astronomytechnologytoday.com.
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Editor’s
Note
Gary Parkerson, Managing Editor
Subscription Renewals The previous issue of ATT, September 2008, was our sixteenth and brought with it numerous questions concerning renewal of subscriptions. Because many of you took advantage of our introductory three-month trial offer before extending that with an annual subscription, your initial subscription period may not have been scheduled to lapse until after the fifteenth issue, August 2008, was delivered. Of course, that has now occurred and it is indeed time for charter subscribers to renew, as have most already. If your subscription was scheduled to lapse, you should have received an email notice of that status well in advance of delivery of your final issue. If you did not receive that notice, you can check the status of your subscription by logging into your account at www.astronomytechnologytoday.com, or you can inquire by email addressed to subscribe@astronomytechnologytoday.com. There are several renewal options including a two-year subscription at substantial discount from the already bargain annual subscription price, and you even have the option of receiving your monthly issue in its online, digital format alone. While on that subject, please remember that the online, digital version of each issue of ATT is available whenever graphics reproduced in the print version fall short of your expectations. All subscribers have access to images of far greater detail and fidelity that high-resolution computer images best provide. Although our interior newsprint pages make possible the unusually low subscription prices you enjoy, they are sometimes inadequate for displaying detail captured by the amazing astrophotographs that often accompany feature articles. Fortunately, the online, digital version of the magazine suffers no such handicap.
issues of the magazine than we had anticipated; so many in fact that supplies of some issues are now very low. That supply may soon be exhausted, so if you want to complete your collection of ATT issues, we encourage you to take advantage of the current discount offers before supplies are exhausted. The price for the complete 16 magazine back issue package has increased to $25 because in September the Postal Service eliminated the least expensive shipping option and we are now sending the packages through Priority Mail.
Back Issues More new subscribers have taken advantage of the discount packages offered on back
Who Writes This Stuff? On occasion, we receive correspondence that questions the advisability of publishing
Corrections As for back issues, William Risen wrote to advise that the cutaway image we included on page 41 of the September 2007 feature article covering the Vixen VC200L actually showed the Vixen VMC200L instead. Ironically, one year later in the September 2008 cover article featuring the Vixen VMC200L, we mistakenly referred to that scope as of “Mak-Newt” design due to editorial error – mine. And yes, Erik Wilcox, author of that article, and I both know what distinguishes a Maksutov-Newtonian from what Vixen describes as the “Catadioptric Field-Maksutov” design of the VMC200L. Although many telescope savvy folks proof each issue of ATT, the buck stops with me on accuracy of its content and I simply blew it in both instances. Similarly, Edward Caferella wrote to advise that after reading Craig Stark's entry in the September Astro Tip column, he attempted to visit "www.luminous-films.com" only to achieve an error report. He tried removing the hyphen (which was added because the URL continued to the next line) and ended up at a site devoted to movie making. His continued tenacity revealed that our errors also included adding an "s" to the address. The correct address is "www.luminousfilm.com".
“reader” provided content, which I take to mean content from other than professional writers or astronomy products industry pros. The fact is that little of the content of ATT is provided by professional technology writers, although we do occasionally bring you the work of authors who have been published as extensively as anyone on the subject. Much of the coverage ATT provides is from industry professionals however. Frankly, we enjoy the insight that only industry insiders can provide and value their contributions here. There is much to learn from those who design, build and market the products we cover and we are grateful for all who are willing to share their experiences with you here. But I hope that you, like I, also find the experiences shared by accomplished fellow amateur astronomers, who use these products on a regular basis, helpful as well. When I want to know what to expect from a specific product, I generally first ask a friend if I know that he or she has experience with it, and that is a large part what we try to duplicate here. So in this issue of ATT, Erik Wilcox will share his experiences with the alt-azimuth AstroLight Newtonians recently introduced by Parks Optical, Dave Snay reports on astro imaging with Orion’s EQ-G mount and StarShoot AutoGuider, and Jason Scherff explains what merit he found in ScopeStuff’s Dob Bearing Rebuild Kits. As for industry-insider coverage, Scott Tucker of Starizona explains in this issue the history of that company’s HyperStar Schmidt Cassegrain Telescope imaging system. Finally, professional offerings in this issue also include Professor Greg Parker’s report on his experiences with imaging with the original HyperStar and new HyperStar III systems. Few would argue that Prof. Parker's accomplishments haven't earned him "Pro" status when it comes to astrophotography publications. Hurricanes and Friends in Low Places I'm writing this column while still feeling soaked and chilled by the rains and winds of Hurricane Gustav. Meanwhile, Hannah has created challenges along the East Coast and we await Ike's arrival. To all our friends who live in low coastal planes, we hope you are safe and that you remain so. I've no idea what the astronomy equivalent of "keep your powder dry" might be, but perhaps we should think of one.
The new Astro-Physics 6" Eagle Adjustable Folding Pier is a versatile work-of-art as well as a totally practical tool for the advanced imager. The one piece assembly sets up quickly in the field and allows adjustment of pier height, leveling of the mount, and eases the process of polar alignment.
www.astro-physics.com • 815-282-1513 Astronomy TECHNOLOGY TODAY
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INDUSTRYNEWS
CARINA SOFTWARE Voyager Version 4.5 Now Available For more than fifteen years, Carina Software has been offering full-featured planetarium software programs and the newest version of its Voyager software program, Voyager 4.5, builds on this experience with one of the most robust software programs available today for amateur and professional astronomers. The new enhancements are many. These include a new look and feel with a multitude of new graphic updates including windows and dialog boxes which now contain native controls that better match the Aqua interface of Mac OS X and the Aero theme for Windows Vista. Its planet, moon, ring, and shadow drawing code has been completely rewritten to include the effects of perspective and rotational flattening. Voyager 4.5 can also export sky charts as JPEG or TIFF files for easy display on web pages or to import into other documents. The Mac OS X version can also export sky charts in PICT format. Other graphic improvements include new planet and moon maps, new digitized sky survey deep-sky object images, realistically rendered stars, a panoramic digital milky way, and wide-field chart projections. Voyager 4.5 also offers several new software engine improvements including the ability to download and import the latest orbit data for comets and asteroids directly from the Minor Planet Center. It can also download and import satellite orbit files in standard NORAD TLE (Two Line Element) format – all to ensure accurate position predictions. It also includes data for nearly one hundred new planetary moons that have been discovered in the 21st century. In addition, you can now customize the display options for every planet and moon in the Solar System individually. View Titan's surface as seen by Cassini’s infrared camera; watch Saturn's “shepherd” moons orbiting outside the delicate F-ring; view the chaotic mix of Jupiter's “temporary” outer moons orbiting in retrograde around the planet. Other engine
improvements include new calendar systems, new asteroid groups, a high-performance implementation of JPL's state-of-the-art DE408 planetary ephemeris, as well as the amazing ability to accurately model the precession of the Earth’s axis and the motions of the stars back to the dawn of humanity. A wealth of new data has been added including textual, plain-English descriptions for hundreds of planets, moons, stars, clusters, nebulae, and galaxies. The program includes an updated image gallery of over 1,400 highquality astronomical images. It also includes the latest version (2006.5) of the Washington Double Star catalog, with information on more than 100,000 multiple systems and over 2,000 binary stars. Voyager 4.5’s basic stellar database is comprised of a combination of data from NASA’s SKYMAP catalog, and the Hipparcos, Tycho-1, and Tycho-2 catalogs. It is a complete and comprehensive compendium of data on more than 2.5 million stars brighter than magnitude 12. Data for more than 38,000 variable stars, and over 100,000 double stars – including more than 1,300 binary systems with orbits – are integrated into the main stellar database. Voyager 4.5’s DVD version expands its basic stellar database by including all stars from the second-generation Guide Star Catalog brighter than magnitude 18 – a total of more than 155 million stars. The software’s deep-sky object database has been completely rebuilt, using data from 21st-century sources wherever possible. The DVD version contains the complete 2003 version of the Principal Galaxy Catalog, containing data on nearly one million galaxies. Voyager 4.5 includes Go-To support for the ServoCAT, Argo Navis, as well as the latest computer-controlled telescopes from Meade and Celestron, including the entire Meade LX-200, LX-200 GPS, and Autostar lines, and the Celestron NexStar, and NexStar GPS series. Many older models, including simple encoder systems, are also supported.
Most telescopes will require a USB-to-Serial adapter. Voyager 4.5 is available for $199.95 for the DVD set and $149.95 for the CD set. Previous owners of Voyager will receive a discount based on the version of the program they currently own. For more information, please go to www.carinasoft.com.
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Telescopes
The AstroTrac TT320X is the new and improved version of the AstroTrac TT320, the innovative motorized camera tracking mount that was introduced by UK based Astro Trac last year. The TT320X tracks the motion of the stars for up to two hours with very high accuracy, eliminating the usual star trails in fixed long exposure images of the night sky or the need to constantly re-adjust manual Alt-Az mounts. It offers a very light and stable mount to build astrophotos with extended exposures, revealing the deeper structure and beauty of the sky. It’s the perfect product for anyone interested in wide-field imaging with a camera and lens, a spotting scope, or telescope, or for anyone wanting to do visual observing using magnifications ranging from low to high power. The TT320X offers several significant enhancements to the original version. These include solar and lunar tracking rates as standard, new drive mechanics, a lighter weight of 2.4 pound (1.1 kg), a longer polar scope arm – which makes for easier polar alignment – and an increased load capacity of 33 pounds (15 kg), an increase of 11 pounds (5 kg) over the original TT320. Because it’s small and portable enough to fit into a camera bag, suitcase, or accessory case, you can take it anywhere you can take a camera and tripod. The TT320X is precision CNC machined to the highest tolerances and is equivalent to a 24-inch diameter worm gear. Preloaded bearings are used to provide smoothness under load. Aluminum and stainless steel are used throughout for lightness, strength and corrosion resistance. Polycarbonate shields (also used for bullet proof glass) protect the drive mechanism from damage. The TT320X draws minimal power, so you get around 10 hours tracking from a set of 8 AA batteries. For more information or to find a dealer visit www.astrotrac.com.
INDUSTRYNEWS
MEADE INSTRUMENTS Introduces mySKY Plus Meade Instruments has announced that it has introduced several enhancements to the popular mySKY, which it is now offering as the mySKY Plus. Included is even more multimedia content featuring new video, animation, music and narration, as well as a more informative introduction and how-to guide on the operation of the device. GPS speed has been improved, so that it takes less time to enter the time, date, and location to be stored in the internal clock and memory. This information is automatically retrieved the next time the mySKY Plus is used, which provides for faster start up. The mySKY Plus utilizes a combination of 12-channel GPS receiver, electronic accelerometers, and magneticnorth sensors that combine to provide highly accurate calculation of the device’s location
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Astronomy TECHNOLOGY TODAY
and pointing orientation. No user input is required – simply turn it on and it automatically acquires all data required to support its numerous functions. The mySKY boasts an upgradable database of over 30,000 objects and delivers celestial information in a true multimedia format. Sight, sound and tactile feedback are simultaneously stimulated by its unique integration of the full color LCD display, clear, concise audio and intuitive pointing design. And, perhaps best of all, with an optional cable, the mySKY controls Meade computerized telescopes. Once aligned, simply point and shoot and the scope moves to any celestial object target. The Meade mySKY Plus Universe Guide also adds GPS capability to nonGPS Meade telescopes. For more information and a list of Meade retailers, go to www.meade.com
INDUSTRYNEWS
NORTHEAST REGION OF THE ASTRONOMICAL LEAGUE
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Presents Stellafane Walter Scott Houston Award to Mike Mattei
Among the festivities of Stellafane 2008 was the presentation of the Walter Scott Houston Award to Mike Mattei. The award was made on August 2 by the Northeast Region of the Astronomical League (NERAL). Mr. Mattei has long been an active member of the Association of Lunar and Planetary Observers and the American Association of Variable Star Observers and also active in amateur telescope making. He eventually made optics his professional and specialized in design and fabrication of optics for the Space Optics Research Labs and Optical Systems and Technology, Inc. With these positions came responsibility
Print and Online Issues Now Available!
for optics used in the exploration of space, including in the Ultraviolet Telescope for the Goddard Space Flight Center. Mike’s career has included work at Lincoln Labs (where he works today) on special “Star Wars” projects involving Laser Imaging Optical Radar Systems and at the M.I.T. Wallace Astrophysical Observatory. His professional experience even extends to teaching at the University of Hawaii. But, Mike is best known for the endless hours he has spent teaching the art of mirror making at the workshops of the Amateur Telescope Makers of Boston. With its Walter Scott Houston Award, NERAL recognizes exemplary service to the League and to amateur and professional astronomy in general. Mr. Houston, the award’s namesake, was a celebrated astronomy author who until his passing guided thousands of observers through his monthly column in Sky & Telecope.
ASTRONOMY
TECHNOLOGY TODAY
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Astronomy TECHNOLOGY TODAY
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INDUSTRYNEWS
e
CATSEYE COLLIMATION Adds New XLS TeleCat/TeleTube Lines and Online Procedures and Instruction Downloads To better serve the growing ranks of owners of ultra-fast Newtonians, Jim Fly, owner of Catseye Collimation, has introduced its new XLS Catseye Sight Tubes. With the rapid proliferation of larger-aperture, low focal ratio Newtonian telescopes with 2-inch focusers, the availability of Catseye’s precision 2-inch XLS Sight Tubes is long overdue. The new tools are designed to permit the user to “see” the oversized secondary mirrors that these scopes require, while remaining flush with the focuser drawtube. First introduced as the TeleTube XL and TeleCat XL, Catseye’s novel “telescoping” Sight Tube collimation tools allow the performance-minded amateur to custom adjust the Sight Tube length for optimum secondary centering under the focuser to symmetrically capture the light cone produced by the primary mirror for maximum illumination and contrast. The XLS version is shorter than its big brother, the XL, and has provision for use with focal ratios ranging from f/3.0 to f/5.0. The appropriate slide position is locked by the user with hex-head set screws and a calibrated focal ratio “ruler” accessory is included to easily establish the required slide length in ratio increments of 0.1. Like the XL series, XLS Slide Tubes are precision machined from T6061-T6 aluminum and black Delrin, and include 90-degree intersecting cross hairs constructed from 0.029-inch stainless steel. The new XLS Sight Tube is available in both the Catseye TeleCat and TeleTube formats and is priced from $95 US. Jim has also announced the
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Astronomy TECHNOLOGY TODAY
introduction of a series of collimation procedure and tool instruction resources that are downloadable from its website in PDF format. The first is a four-page document that covers general Catseye Newtonian collimation procedures. The document details steps for insuring initial mechanical alignment of the focuser to the tube axis, primary mirror to the tube center, secondary mirror diagonal to the tube axis and focuser, as well as secondary diagonal tilt. The resource then explains the general procedures for using the Catseye, Blackcat or Telecat tools to accomplish these steps. The second document provides three pages of in-depth instruction on center spotting the primary mirror with the classic Catseye precision selfadhesive triangle target. A third, sixpage document provides extensive instruction for use of the Teletube XL and Telecat XL adjustable sight tubes. Finally, a five-page document details effective procedures for use of the Infinity XL Autocollimator, the tool that set a new benchmark in visual clarity of alignment of optical elements and resulting collimation precision. The Catseye Collimation website also offers a handy utility for calculating proper diagonal mirror offset. For these and other Catseye resources, please visit www.catseyecollimation.com.
INDUSTRYNEWS
STARK LABS Releases Nebulosity 2.0 and PHP Guiding 1.9 Stark Labs produces an array of affordable (if not free) software for astrophotography. Earlier this year, we called Nebulosity a “certified best buy for image capture and processing” when reviewing Version 1.7.4. Since its initial release several years ago, users have watched it grow over the course of over 40 free updates. Craig Stark, owner of Stark Labs, reports that he “wanted to make a number of sizeable changes to the code that would allow for future expansion,” and after many months of development, Nebulosity 2 has been released. Like the earlier versions, Nebulosity 2 is a cross-platform (Mac and Windows) image capture and processing application supporting a very large array of cameras (Atik/Artemis, Canon, CCD Labs, Fishcamp, Meade, Opticstar, Orion, QHY, QSI, SAC, SBIG, Starlight Xpress). Rather than attempt to do everything in a single package, the aim of Nebulosity 2 is to provide a simple, clean interface during image capture and to provide the tools novices need to make a picture ready for final touch-up and the tools anyone would need to complement software like PhotoShop. New in Version 2 are numerous features including a customizable GUI layout that includes camera-specific controls for SBIG
and QSI cameras, a notes tool, and a history tool. Also new are a curves tool, a new noise reduction tool, an improved fine-focus tool using the half-flux density radius metric for precise focus, and a link to PHD Guiding (V 1.8). This link to the popular PHD Guiding autoguiding package from Stark Labs enables users to “dither” the location of the images
across frames and to pause guiding while the main camera downloads images. Also new to the Mac version of Nebulosity 2 is support for the QHY8 and QSI 500 series cameras and to the Windows version is support for ASCOM-5 compliant cameras. The price for Nebuosity 2 is $60 and Nebulosity 1 users are able to upgrade their licenses for $15. Stark Labs has also announced the latest
iteration of PHD Guiding software, Version 1.9. As with the earlier version, PHD Guiding 1.9 offers a simple, clean interface that is designed for ease of use. It offers arbitrary camera orientation, pixel size, scope focal length, etc., measured during the automatic calibration process. It provides guides for several options for lag-free, accurate commands on a wide range of mounts including: ASCOM’s PulseGuide (Windows); ShoeString Astronomy’s GPUSB (Windows & OS X); GPINT (Windows) ST-4 style adapters; Pierro Astro’s USB Guiding interface; and through a camera’s onboard output port if present. PHD Guiding 1.9 also allows stacking shorter subframes on the fly to extend effective exposure duration on short-exposure cameras, guiding in RA and Dec, intelligent automatic unidirectional and manual unidirectional Dec guiding modes, automatic sizing and stretching of guide image for display purposes, image noise reduction with or without dark frames, and real-time plotting of performance. The software supports cameras from many popular manufacturers including Atik, SBIG, CCD-Labs, Meade, Orion, SBIG, and others. For more information, see www.starklabs.com.
Astronomy TECHNOLOGY TODAY
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ASTRONOMY SHOPPE New Scope-Scout Bracket The Astronomy Shoppe now offers a Scope-Scout Bracket which can turn any scope into a “push to object locator,” utilizing Celestron’s SkyScout Personal Planetarium. The bracket will work on virtually any scope that has a standard Vixen/Orion dovetail finder bracket, features a threepoint tilt to properly align the SkyScout, and is modular so that it can be removed from a telescope and attached to binoculars. This unit is shipped complete with all mounting hardware for the SkyScout. It includes the bracket and dovetail adapter with stainless steel 1/4-20 thumbscrews and three nylon thumb screws. Also available are custom adapters for older Meade and Celestron SCTs.
D O B S E R VAT O R Y
Our newest offering, the Dobservatory is specifically designed for the low pivot point of DOBs allowing you to view near the horizon. The Dobservatory is available in sizes from 7'6" x 7'6" to 15'6" x 15'6".
Each kit contains a Scope-Scout Bracket with three nylon leveling screws, one stainless 1/4-20 connector, a dovetail adapter and quick-disconnect stainless steel thumbscrew. Also available is a centering table with a stainless steel 1/4-20 replacement screw for the SkyScout. The Scout-Scout
Bracket kit is $59.99 US and can be upgraded to include the centering table and hardware for $79.99 US. For more information, go to www.astronomy-shoppe.com.
The Home Model is the perfect design of form, function and, of course, pricing with every feature you’ll need for the ultimate in observing! The Home Model is available in sizes from 7'6" x 7'6" to 15'6" x 15'6".
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STELLARVUE Introduces SV70ED Refractor Vic Maris of Stellarvue has done it again with the introduction of the new SV70ED, featuring the lowest price ever offered on a Stellarvue ED refractor – only $399 US, including case! Weighing in at only 4.5 pounds and with a mere 12-inch length with dew shield retracted, the SV70ED is the perfect travel scope. It features a 70-mm f/6 doublet made with a hand figured, extra low dispersion Stellarvue doublet lens and uses the same ED elements as Stellarvue’s 80ED and 102ED apos, producing excellent color correction and extreme contrast. It also includes a 2-inch dual-speed Crayford focuser, retracting dew
shield, threaded dust cap with SV logo, Vixen-style mini rail for direct attachment to most mounts and camera tripods, and hard side, foam-lined case. The focuser features full 360 degree rotation and is equipped with a 1.25-inch adapter. The scope is powder-coated in an attractive white finish with a silkscreened Stellarvue logo and looks as good as it performs. Stellarvue is currently taking preorders for October delivery and this scope is sure to be a popular stocking stuffer (and it will probably fit most stockings!) For more information, go to www.stellarvue.com
More options, Most roll-off roof experience, 25 years construction experience, Turn-key installation, Ever customizable designs, Highest quality residential specs (not shed type construction), Heavy duty industrial capacity roller system design, Exclusive m1 OASYS roof automation, Standard and Heavy Duty roof motor designs, Big Bear Piers, Warm/Control room options, Plans available created by an experienced builder/astronomer with DIYers in mind, Our observatories have been chosen 10 to 1 over other commercially built observatories at Deerlick Astronomy Village.
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SCOPESTUFF NewStuff from ScopeStuff ScopeStuff regularly introduces so many new items that it’s easy to miss the significance of individual products. Here’s some new stuff you’re sure to find particularly interesting. C-Mount to 2-inch Eyepiece Barrel Adapter with Filter Threads ScopeStuff's Model C2BF mount screws into the front of video cameras that use the C-mount and CS-mount formats and adapts to a 2-inch eyepiece barrel. There is no stop or “shoulder” on the 2-inch barrel, which design allows the camera to be positioned as close to the focuser as possible, avoiding the in-focus issues video cameras present many telescopes. But the mount doesn’t stop there. It also features 1.25-inch and 2-inch standard female filter threads to facilitate the use of both filters and focal reducers. The mount is constructed of precision milled, black anodized aluminum and has a 1-inch barrel length and 1.15-inch overall length. That length can be extended if needed by an additional inch with ScopeStuff's Model EPE2 filter thread barrel extension. The C2BF mount is priced at just $44 US and the EPE2 barrel extension is $19 US. Negative Profile Eyepiece Adapter, 1.25 Inch to 2 Inch If you need more in-focus with 1.25inch eyepieces and accessories in a 2-inch focuser, then ScopeStuff's new Model
NPEA Negative Profile Eyepiece Adapter is your solution. It allows the eyepiece to be inserted more than 3/4 of an inch farther than with a typical “low-profile” adapter. The NPEA inset adapter accepts eyepiece and accessory bodies up to 1.75 inches in diameter and holds such accessories securely with two rounded-tip setscrews. The 2-inch barrel is 1.6 inches deep below the top flange or shoulder, and has an overall height of 1.75 inches. It is constructed of black anodized, precision machined aluminum, uses two stainless steel, rounded tip setscrews, and weighs approximately 4 ounces. The ScopeStuff Model NPEA adapter includes an Allen wrench and is priced at just $39 US. True 2-inch Barrel to Canon EOS Adapter ScopeStuff's Model B2CL adapter attaches directly to the standard lens receiver of Canon EOS cameras and mounts to the telescope with a 2-inch barrel. This configuration results in a full 1.75-inch unobstructed opening to match the 1.75-inch interior diameter of the camera's female lens mount. The 2-inch barrel of the adapter is even threaded to accept 2-inch filters. The result is a Canon EOS mount system that provides the shortest possible focus length for SLRs in 2-inch focusers and accessories, the largest possible unobstructed aperture, and a place to put 2-inch filters. The barrel length of the B2CL adapter
is 1.25 inches. This length can be increased by an additional inch by using the ScopeStuff Model EPE2 filter-threaded 2inch barrel extension. The Model B2CL adapter is priced at $49 US. Adapter Plate for DSI Pro Series Cameras ScopeStuff’s Model DSIF adapter plate replaces the factory filter slide adapters of Meade's DSI Pro, Pro II and Pro III cameras and features T-threads and 1.25-inch format filter threads. It’s very low 0.3-inch profile permits the use of filter wheels and other accessories with minimum back focus. It is constructed of black anodized aluminum, with stainless steel hardware. The Model DSIF adapter plate is individually priced at $39 US, or can be purchased in combination with ScopeStuff's Model DSIB shutter for DSI Pro series cameras for just $72 US. 2-inch Low Profile T-adapter for Direct Photography This unique adapter features a 2-inch male barrel and male T-threads, as well as a very low profile – the setback is just 0.325 inches. The Model TA3P adapter is assembled using ScopeStuff's Model TAEP and TALP adapters, so you actually get three adapters in one. The nose of the 2-inch barrel is threaded for 2-inch format filters and the entire assembly is of black anodized aluminum. The Model TA3P 2-inch Low Profile T-adapter for Direct Photography is priced at $49 US.
Astronomy TECHNOLOGY TODAY
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NEWPRODUCTS
FLEMING ASTROPHOTOGRAPHY Astrophotography Tutoring Service Neil Fleming of Fleming Astrophotography has announced a new astrophotography tutoring service. This service offering is oriented towards any budding astrophotographer who desires one-on-one tutoring to “get over the hump” that many experience while progressing in this hobby. Fleming states, “We've all seen DVDs, read books, and gone to conferences inperson, but if you’re anything like me, you prefer to be shown how to do things in person. I’m setting up real-time tutoring that allows us to collaborate on either your computer or mine…with your images or prepared material. The format is a dedicated evening, say 2-3 hours. By using remote access facilities, we would collaborate on one system, either yours or mine.” Topics include initial image processing with CCDStack, MaxIM,
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Astronomy TECHNOLOGY TODAY
Deconvolution and DDP, tools like Registar, Tria, FocusMagic, image acquisition and guiding techniques with MaxIM or CCDSoft, automation approaches with CCDCommander or CCDAP, mount alignment with T-Point or PoleAlignMax, and use of FocusMax. Also available is tutoring on the myriad possible techniques in Photoshop including data optimization, advanced selections and layers, sharpening (Smart Sharpen, Unsharp Masking, “True” Unsharp Masking, Multi-layer High Pass Sharpening), color balancing and adjustments, gradient control, and mosaics. Fleming is a noted astrophotographer, specializing in the capture of very highquality images from light-polluted locations, such as those in the Boston area. His images have been published in both Sky & Telescope and Astronomy magazines, and
featured on the popular, "Astronomy Picture of the Day" (APOD) site. Additionally, his imagery was included in Timothy Ferris’ PBS documentary, Seeing in the Dark. His speaking engagements have included such popular conferences as the Midwest Astro-Imaging Conference, the NorthEast Astro-Imaging Conference, as well as the Astro Imaging Conference in San Jose, each an annual event oriented towards astrophotographers wanting to learn more about the techniques used for advanced image processing. Neil is the Director of Professional Services for Lumigent Technologies, Inc., a firm specializing in database auditing software for Application GRC and regulatory compliance in areas such as Sarbanes-Oxley. For further information, please visit www.flemingastrophotography.com.
NEWPRODUCTS
APM TELESCOPES High Brightness R-G-B 50 Micron Artificial Star and Deluxe Doublet ED Binocular The APM high-brightness R-G-B 50Micron Artificial Star provides a convenient, stationary pin-point of light for “star collimation” and “star testing” of telescopes of any design. Performing these tests on a real star requires the tester to await rare clear, steady nights and presents the added challenge of keeping the star perfectly centered in the field of view as it transits the night sky. APM’s new artificial star not only solves these problems by producing a perfect, stationary, 50-micron high-brightness ‘star’ that can be used at any time, it also provides the option of testing in the individual light wavelengths of red, green and blue, or combining them to produce a more typical white spot. Star testing in the three individual primary colors allows the tester to determine at which wavelengths the optic system is best corrected, as well as the focus shift of the telescope. Minimum recommended operating distances range from 6 meters for telescopes of 80-mm aperture to 39 meters for those of
500-mm aperture. Made in Europe, it is powered by a standard 9-volt battery (included) and features separate switches for red, green and blue wavelengths. The retail price for the APM R-G-B 50-Micron Artificial Star is $179 US, including shipping to customers in the US. Over the years, APM has introduced a number of refinements to its standard 20x/40x 100mm 45 degree Binocular, earning worldwide popularity for that product. While the Standard Version is still in production and continues to be available, APM has introduced a Deluxe Version that features improved color correction, contrast, and light transmission thanks to a new doublet ED objective design. This premium binocular retails in the US for $895. Included with the Deluxe Version are
1.25-inch eyepieces that feature a 5-element 70 degree wide-field design and provide higher magnifications of 25x and 50x. The eyepieces are threaded to accept standard filters. A photo-tripod port with 1/4-20 thread is also included for use with the photo-tripod adapter of the Deluxe Version Binocular, as well as a durable aluminum case with custom fitted foam insert. It offers fully-multicoated doublet ED with high-quality Bak4 Fully-Multicoated Prisms. The eyepiece diameter is 1.25 inch (many standard 1.25inch eyepieces will reach focus), has an eye relief of 16 mm at 25x and 10 mm at 50x, and offers an angle field of view of 2.9 degrees at 25x and 1.5 degrees at 50x. Weighing in at 14.5 pounds, it is 19.7 inches in length, 9 inches in width, and 5.2 inches in height. For more information go to www.apm-telescopes.com.
Astronomy TECHNOLOGY TODAY
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NEWPRODUCTS
ORION TELESCOPES & BINOCULARS More New Products for the Fall The folks are Orion have been busy this year. In last month’s issue of ATT we featured three new products they introduced this fall and now they tell us there’s even more! Orion’s new HighLight Barlows deliver big power and premium performance. With a strong 3x or 5x magnification, they’re ideal for high magnification lunar and planetary observation, and for imaging with a solar system camera or webcam. They’re also great for pumping up the power of short focallength telescopes. The HighLight Barlows employ a sophisticated 5-element lens configuration engineered to render optically flatter, sharper images than standard barlows. The lenses are fully multi-coated to ensure high light throughput, and their edges blackened for improved contrast. The machined aluminum, anodized barrels are also blackened inside and glare threaded to prevent internal reflections. A non-marring compression ring secures the eyepiece in place. Slotted barrels prevent accidental slip-outs, and dual rubber grip bands on the housing ensure easy handling. The HighLight Barlows require no additional inward or outward focus travel and are available starting at $139.95 US. Orion’s new SkyGlow Imaging Filters
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Astronomy TECHNOLOGY TODAY
are designed for deep-sky imaging under light-polluted skies with CCD or DSLR cameras. The filters (available in 1.25-inch and 2-inch sizes) suppress up to 99 percent transmission of specific wavelengths responsible for light pollution and enhance the contrast of all types of deep-sky objects, including galaxies, nebulas, and star clusters. Furthermore, they preserve neutral color balance, eliminating need for corrective color processing later and enable longer exposure times without background saturation due to sky glow. The filters are available for $119.95 US for the 1.25inch filter and $159.95 US for the 2-inch filter. Orion has also introduced the new SkyQuest XX12 IntelliScope Truss-Tube Dobsonian, a traditional 8-pole truss scalable design which offers superior rigidity and performance. The huge 8inch altitude bearings with adjustable CorrecTension and EbonyStar on Virgin Teflon azimuth bearings provide silkysmooth altazimuth motion and the 12-
inch (305-mm) parabolic low-expansion Pyrex optics (f/4.9) pack a serious punch for deep-sky observing. Included is the IntelliScope computerized object-locating technology, which pinpoints any of 14,000 objects in seconds. Also included is Starry Night Orion Special Edition software, now with telescope control functionality compatible with the IntelliScope system. The telescope features a dual-speed (11:1) 2-inch Crayford focuser, 9x50 finder scope, DeepView 2-inch and Sirius Plossl 1.25-inch eyepieces, Cooling Accelerator Fan, eyepiece rack, dust caps for top and bottom tube sections, and more. The deluxe 12-inch truss tube Dob disassembles for easy transport to any observing site and all truss assembly knobs are captive for no-tools-required hassle-free tube assembly and disassembly. Introductory pricing for the SkyQuest XX12 IntelliScope TrussTube Dobsonian is just $1299.95 US. For more information visit www.telescope.com.
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FARPOINT ASTRONOMICAL RESEARCH Introduces 2-inch Desiccant Caps Farpoint Astronomical Research, maker of the popular FAR-Sight Binocular Mounting and Targeting System, has announce the introduction of a desiccant system for use in Schmidt Cassegrains, refractors, and any other telescopes using a standard 2-inch visual back. The desiccant holders are designed to protect the interiors of compatible telescopes from moisture and corrosion, while serving to cap the focuser as well. The desiccant caps are precision CNC milled from premium aluminum and then anodized to provide an attractive and durable finish. Each cap is delivered with six desiccant
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Astronomy TECHNOLOGY TODAY
recharges (18 individual packets) and is priced at just $44.95 US. For more information on this and other Farpoint Astronomical Research products, visit www.farpointastro.com.
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The Evolution of Intelligent Design A History of Starizona’s HyperStar
By Scott Tucker
Any device that claims to inexpensively convert a mass-produced SchmidtCassegrain telescope into a high-speed, wide-field imaging system with excellent optical performance, sounds too good to be true. Telescopes for imaging are supposed to be expensive and astrophotography is supposed to be hard. At least, that used to be the way everyone thought. But times have changed and technology has made astrophotography accessible to almost any amateur astronomer. Computerized telescopes and inexpensive CCD cameras have put equipment within the reach of the average stargazer. Now Starizona’s HyperStar system makes deep-sky imaging not only affordable, but also extremely easy. In 1997, Celestron released the Fastar 8 telescope. The scope featured a removable secondary mirror, allowing a Fastar lens to be installed, converting the scope from f/10 to f/1.95. This resulted in a 25fold increase in speed, shortening exposure times dramatically and providing a much wider field of view. At the time, only relatively small CCD sensors were available to most amateur astronomers. The short focal
length of the telescope in Fastar configuration was ideal for these smaller cameras. In particular, the Fastar was designed to work with the Pixcel-255 camera, an SBIG system sold through Celestron. An upgrade of the camera to the Pixcel-237 model (later sold directly through SBIG as the ST-237 and then ST-237A), provided a larger chip, but was still small compared to most of today’s cameras. People seemed slow to catch on to the Fastar idea. Ten years ago most astrophotographers still used film, and a common lament regarding CCDs was that the field of view was too small, due to the small size of the sensors compared to film. Also, there may have been a belief that astrophotography was just supposed to be difficult. After all, the great historical astrophotographers like E. E. Barnard spent hours taking single exposures. There was a sense of pride in a kinship with the masters, spending hours
standing behind a scope, manually guiding through a crosshair eyepiece, wondering what in the world that noise was in the bushes. There was a certain machismo in being an astrophotographer, and the rewards for one’s efforts were perceived to be greater because of the difficulty involved in obtaining them. Fortunately that mindset began to change, but it has been a slow revolution. The Fastar 8 was never a big seller, but Celestron began to include the Fastar option on their popular computerized telescope, the Ultima 2000. The start of the computerized telescope age helped to popularize Fastar, but still relatively few astronomers were using the system. After spending some time with the Fastar system, Starizona realized the potential for highAstronomy TECHNOLOGY TODAY
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HYPERSTAR THE EVOLUTION OF INTELLIGENT DESIGN
Rosette Nebula – Image by Steve Loughran, HyperStar C8, QHYCCD QHY8 CCD Camera
speed CCD imaging. But there were still shortcomings, primarily in the limited size of the CCD cameras available. Still, as a means of getting successful results right away for a new astrophotographer, Fastar was a great system. Celestron also released a Fastar lens for their 14-inch SCT, converting it from f/11 to f/2.1. However, like the 8-inch Fastar, the lens was designed to match the Pixcel cameras. As the digital photography revolution advanced, it became apparent that there would come a day when astrophotographers would outgrow Fastar. Once bigger CCDs became available to more astronomers, Fastar reached its limits. Dean Koenig, owner of Starizona re-
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calls his first experience with Fastar. “I was always an ‘oh, wow’ kind of observer; I loved visual observation. But the very first night I used a Fastar telescope, I was hooked on imaging. I was amazed that in a single 30-second exposure, I could see more than at the eyepiece of my 20-inch Dobsonian. I was sold.” Koenig also realized the limitations of the system. So he posed a question to a friend and experienced optical designer. Was it possible to improve on the Fastar system? The answer came back “yes,” and HyperStar was born. Fans of Celestron’s Ultima 2000 telescope had long been waiting for the day when the company introduced an 11-inch
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go-to SCT. That day finally arrived with the release of the NexStar 11 GPS. In addition to providing lots of aperture with computerized functionality, the telescope featured the removable secondary mirror associated with the Fastar system. Many users of the NexStar 11 began eagerly awaiting the Fastar lens itself. However, production never began on the 11-inch Fastar lens. Conveniently, at the same time, the HyperStar lens from Starizona was finally coming together. In 2002, Starizona released the first HyperStar lens, designed for the 11-inch Celestron. It improved on the Fastar lens in three regards: speed, performance, and compatibility. The first HyperStar converted the telescope to f/1.8, a 30-fold increase in speed over the standard f/10 configuration. The optical performance was improved over the original Fastar lens. And, perhaps best of all, the lens was compatible with a wider range of cameras. The Fastar lens was optimized for use with the 6-mm sensor in the Pixcel-237 camera, while the new HyperStar lens accommodated sensors up to 11 mm. With the introduction of HyperStar, high-speed CCD imaging started to become more popular, but again, the idea was slow to catch on. Larger CCDs and digital cameras began to bring about the death of film photography. Astrophotographers were starting to embrace the age of digital imaging. But the long-exposure mindset still existed. Plus, there was an ingrained opinion that mass-produced SCTs simply were not cut out for high-quality as-
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HYPERSTAR THE EVOLUTION OF INTELLIGENT DESIGN
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M8 – Image by Gil Esquerdo, HyperStar C11, Starlight Xpress SXVF-H16 Camera, telescope in alt-azimuth mode
trophotography. Premium apochromatic refractors remained the telescope of choice for wide-field imaging. Starizona followed up the 11-inch HyperStar lens with a model for the Celestron 14-inch SCT. The larger aperture of the C14 allowed for a larger CCD sensor to be used; in the first HyperStar C14 lens, up to a 15-mm sensor could be handled. At f/1.9, the HyperStar C14 was nearly 25 percent faster than the original Fastar. I recall the first night out with Dean Koenig and the HyperStar C14. We tested the lens on David Levy’s 14-inch SCT at Levy’s observatory south of Tucson. We used the SBIG ST-10 camera for which the HyperStar had been optimized. Our first target was the Trifid Nebula. We aimed the telescope and took a 60-second exposure,
assuming this would be sufficient to at least see the object. We were using the first-generation ST-10, which used a parallel port connection. There was a 3-minute download period, which I think only added to the suspense of seeing the first image through the new HyperStar. When the image finally displayed on the computer screen we were amazed to see that not only was the Trifid there, it was completely overexposed! We shortened the exposure first to 30 seconds, then to 10 seconds, before getting an image that looked right. I remember laughing the entire time, thinking of all the time I had spent guiding 2-hour astrophotos with film – and here was a deepsky object in 10 seconds! A HyperStar lens for the 8-inch Celestron soon followed, making high-speed imaging available to users of the most pop-
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HYPERSTAR THE EVOLUTION OF INTELLIGENT DESIGN
M31 – Image by Fred Lehman, HyperStar M14, Starlight Xpress SXVF-M25C Camera
ular-sized telescope. It was then discovered that Meade was shipping certain telescopes with removable secondary mirror assemblies. There were no comparable Fastartype lenses from Meade, it just happened
that the way in which the secondary mirror assemblies were mounted, they were easily removable. A HyperStar lens for the 10inch Meade was the next in the HyperStar family.
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The first major step toward the current line of HyperStars came with the design of the HyperStar lens for the Meade 14-inch SCT. Starizona went back and re-evaluated the design of the HyperStar to see what the ultimate limits of the design were. At the same time, the popularity of using digital SLR cameras for astrophotography was growing. The HyperStar M14 was thus designed to be compatible with not only CCD cameras, but also DSLRs. HyperStar could now cover sensors up to 27 mm in size. The HyperStar C14 was redesigned to take advantage of the improved performance. As larger cameras became less expensive and available to more imagers, the demand for larger-format HyperStar lenses for the smaller telescopes grew. In early 2008, Starizona released the HyperStar 3 lens for the 8-inch Celestron, followed a few months later by the HyperStar 3 for the Celestron 11-inch. Both the 8-inch and 11-inch systems had been through two previous generations, improving optical performance and mechanical design, but remained limited to 11-mm sensors, hence the new models being designated HyperStar 3. 27-mm sensors were now compatible with most of the HyperStar lenses, and DSLRs in particular could be used with the 11- and 14-inch models. Eventually, Celestron discontinued outfitting their telescopes with removable secondary mirrors. Also, the increasing popularity of the system made for a demand for older telescopes or new models without removable mirrors to be used with HyperStar. Starizona began manufacturing conversion kits to retrofit non-compatible telescopes to allow use of HyperStar lenses. The HyperStar takes advantage of the fact that the primary mirror of an SCT operates at f/2. Thus the HyperStar is a field corrector rather than a focal reducer. Normally, the secondary mirror provides a 5x magnification factor, yielding an f/10 system with focus at the back of the telescope. By removing the secondary mirror, focus is moved to the front of the telescope, and the
HYPERSTAR THE EVOLUTION OF INTELLIGENT DESIGN focal ratio goes to f/2. However, removing the secondary mirror induces aberrations that the secondary normally corrects, primarily spherical aberration. The HyperStar lens corrects not only for this aberration, but also coma, astigmatism, chromatic aberration and field curvature. The result is excellent optical performance across a very large field of view. The telescope in HyperStar configuration outperforms the native f/10 system. In fact, stars are up to 12 times smaller at f/2 than at f/10, over the same size sensor. Performance rivals that of the best apochromatic refractors. Measurements of star sizes in images taken through a 4-inch apo refractor and a HyperStar C14 with the same camera are identical. Plus, the HyperStar system has an extra 10 inches of aperture and a focal ratio 8 times faster! To arrive at this level of performance, a new mechanical feature had to be introduced into the HyperStar lens: the ability to collimate. It was discovered that performance, especially with the larger-format versions of the lenses, was not always equal across the full field. This is due to the fact that the primary mirror of the telescope is not always perfectly orthogonal to the optical axis. This can normally be compensated for by collimating the secondary mirror, but with HyperStar there is no secondary mirror. By making the HyperStar lenses collimatible, Starizona allowed the system to reach its full potential. Collimation is easily achieved with three sets of thumbscrews. To compliment the collimation system, the HyperStar lenses also feature independent camera rotation, allowing the camera to be oriented as desired while retaining the collimation of the system. All components of the HyperStar lenses are manufactured in the USA and are hand assembled at Starizona. A HyperStar lens includes a counterweight (except for use with German equatorially mounted telescopes, where it is unnecessary), a holder to protect the secondary mirror while out of the telescope, and a custom-fit hard carrying case.
An adapter for one camera is included with the HyperStar lens, while others are available optionally. Each camera requires a separate adapter in order for the distance from the HyperStar lens to the camera’s focal plane to be set correctly. This distance is very critical at f/2 and is crucial to getting the ideal performance out of the lens. Switching from the standard f/10 configuration to the f/2 HyperStar mode takes just a couple minutes. Replacing the secondary mirror to go back to f/10 is equally quick. Collimation is retained thanks to an indexing pin and notch on the secondary mirror assembly, so no adjustment is necessary after using the HyperStar. Starizona’s website features a short video showing how simple it is to install a HyperStar. The high-speed imaging revolution is finally sweeping through the astrophotography community. Now compatible with a wide variety of cameras, the HyperStar system has become extremely popular. Once thought of as a useful gadget for new astronomers just getting their feet wet in as-
trophotography, HyperStar has become a mature imaging system, providing ease of use for beginners and high performance for advanced imagers. I’m convinced the future of astronomy is imaging. The number of amateur astronomers engaged in astrophotography is growing rapidly. As light-pollution becomes ubiquitous, imaging becomes ever more essential to seeing the wonders of the night sky. HyperStar can be used like an extension of visual observing. The images come down to the computer with very little delay, and with typical exposures of 30 seconds, there is hardly any wait whatsoever. In fact, with a high-sensitivity video system, such as the Mallincam or Stellacam, it is possible to do deep-sky imaging in real time, making HyperStar the perfect teaching tool for schools, planetariums, and star parties. Now that amateur astronomers have realized it’s not necessary to wait and suffer to take astrophotos, the future of astronomy is here now.
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Deep-Sky Imaging with Starizona’s Hyperstar How the New Forest Observatory Re-discovered the Hyperstar By Greg Parker
I took my very first deep-sky HyperStar image of M42 (see Practical Astronomer magazine, December 2007 issue, page 8) back in November 2004 from my New Forest Observatory in Brockenhurst, Hampshire, U.K. (www.newforestobservatory.com), shortly after buying the SXVH9C one-shot colour CCD from Starlight Xpress. In fact, I bought the HyperStar to go with my Celestron Nexstar 11 GPS scope over two and a half years earlier as it was always my intention to carry out deep-sky imaging. My decision to choose the Celestron scope in the first place was dictated by this amazing HyperStar device. I knew nothing about imaging at the time, but the concept was really cool (to me at least), and the scope with the HyperStar fitted looked like such a strange beast that I simply had to own one, if only to see how this thing actually worked. The first HyperStar I bought from Starizona had no adjusters at all, not for collimation or for camera rotation, and it now
seems incredible that the first time I bolted that HyperStar to the C11, I achieved almost perfect collimation. I won’t bore you with my particular learning curve of first going to equatorial mounting and then finding out about taking large numbers of sub-exposures and adding them altogether; instead I’ll go straight to the turning point of my HyperStar experience. One evening I wanted to image both M81 and M82 in the same field of view, but this meant the HyperStar would need rotating. No bother! I reached into the dew-shield and gave the whole secondary cell assembly a twist of a few degrees. I then took a sub to see what I got, and of course it was disaster time! I had completely lost the collimation, the star shapes were all peculiar, and I walked away feeling sick – for about a week. When the panic finally subsided and commonsense returned, it was clear to me that there was a position of perfect collimation (there was at least an existence proof). So the prob-
lem now became, how was I to return to this “magic” position? The whole secondary mirror assembly had a clearance approaching 1 mm all around its circumference within the corrector plate, so I drilled four holes in my beloved C11 and fitted four screw rods at 90 degrees to each other as shown in Image 1. These screw rods allowed the secondary mirror assembly to be moved around within that 1-mm clearance in the collector plate, and by trial and error I could once again return to a collimated optical system. Fortunately, it really wasn’t too difficult to achieve reasonable collimation, although to tell the truth, I never managed to get back to the level of collimation that I hit the very first time just by pure luck. Then there followed a period of two years imaging with this wonderful system, and together with Noel Carboni (Florida, U.S.A.), who carries out all the image proAstronomy TECHNOLOGY TODAY
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DEEP-SKY IMAGING WITH STARIZONA’S HYPERSTAR cessing work on my raw data, we turned out some pretty impressive HyperStar deep-sky images [Image 2 seen on pages 40-41, and the image on cover]. It should be noted that we were doing this at a time when the consensus opinion was that you simply couldn’t take high-quality images with the HyperStar system! Many deep-sky imagers on the forums were adamant that the HyperStar simply wasn’t up to the job. I tried to get the message across that it was capable of stunning images – if it was properly collimated to the optical system – but my words largely fell on deaf ears. The large output of work that followed over the next two years formed the basis of two major Exhibitions of deep-sky images held at the University of Southampton and at the main exhibition hall in Brockenhurst. There were around 50 framed A1 and A2 prints presented at each venue. In addition to the Exhibitions, many of the HyperStar images appeared in U.K. astronomical publications, including Astronomy Now and Sky at Night Magazine. The New Forest Observatory also appeared on BBC TV’s “Inside Out” programme and on ITV’s (independent channel) Meridian News. Finally, HyperStar images also appeared in the national daily newspapers, the Daily Mail and the Daily Express, so the amazing images that were the result of the innovative HyperStar system were being brought to the attention of a large U.K.-based audience. Towards mid-2006, I fancied a change. I wanted to be able to take images with a bigger CCD camera, the Starlight Xpress SXVF-M25C, which is a 6-megapixel CCD compared to the SXV-H9Cs 1.4 megapixels, and I was also getting more than a little tired of collimating my rather Heath-Robinson setup on a fairly regular basis. To this end I changed my imaging system completely to a Takahashi Sky 90 refractor at f/4.5 as the main imaging scope, and the large SXVF-M25C one-shot colour camera as the main CCD imager. My beautiful C11 was now relegated to the role of guide-scope! For nearly a year and a half I worked with the new setup and it was refreshing to
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DEEP-SKY IMAGING WITH STARIZONA’S HYPERSTAR have such a large, flat, field of view with good star shapes across the whole 3.33 x 2.22 degrees this system gave me. I took some pretty fine images with this system, but these were marathon imaging sessions taking many hours of valuable imaging time to produce high-quality images. For example, the images of M31 and the Veil Nebula [Images 4 and 5 seen on pages 40-41] took in excess of 30 hours each of total imaging time, including narrowband data on top of the oneshot colour data. It should be noted that it took Noel Carboni about the same amount of time to process the data as it took me to acquire it in the first place. Taking images this way was proving to be very costly of our valuable time! I was fortunate enough to be on a year’s sabbatical leave from the University of Southampton during this period, so I could be out imaging every clear night, all through the night. But this luxury was due to come to an end in June 2008 and I was at a loss as to how I was to continue to turn out the volume of work.
On returning to the University in June 2008 there was an unexpected chain of events. I was to go out to Phoenix, Arizona, to accept some semiconductor deposition equipment for the University’s new clean room facility. As we know, Arizona means Starizona, and I let Dean know I would be out there for a few days. To cut a long story short, Dean shipped the new version III HyperStar and a Starizona MicroTouch focuser to my hotel in Phoenix and I Image 1 The original Hyperstar Setup Showing the Added unpacked all the goodies the Adjuster Rods second I got back to the New Forest Observatory. way around, and I couldn’t figure out how I know I shouldn’t have attempted to the HyperStar fitted to my scope, as I hadn’t get the HyperStar up and running whilst still realised it came with the secondary mirror jet-lagged, but I ignored my family’s warnholder already fitted, and this needed to be ings and tried anyway. I managed to put the removed to fit the HyperStar to the C11. cog on the MicroTouch focuser the wrong Dean came to the rescue as usual, and a cou-
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DEEP-SKY IMAGING WITH STARIZONA’S HYPERSTAR ple of e-mails later and I managed to put my new HyperStar III system together – and of course it’s just wonderful! The new version III Hyperstar fitted to the C11, prior to the connecting wires being brought out at 90 degrees to one another, can be seen on page 35. The new version III HyperStar has collimation and camera rotation adjusters built-in, so it is a complete doddle to get excellent collimation, very quickly, with the help of CCDWare’s CCDInspector
38 Astronomy TECHNOLOGY TODAY
(www.ccdware.com). In fact, I got better collimation using just 15-minutes of setting up time with the HyperStar III than I ever managed to achieve with the Sky 90 and SXVFM25C combination, so this was a very promising start. First light for the new HyperStar was the central part of NGC7000, and for this image I used manual focus as I hadn’t managed to set up the MicroTouch focuser at this time. Noel Carboni worked his magic on the raw NGC7000 data and the result can be seen in
Image 6 on page 40. I was highly impressed at the star quality corner to corner, and the small amount of vignetting present was no worse than that I had seen with the Sky 90 at f/4.5. But of course, the main thing was that this image only took 56-minutes of total exposure time! I had returned once again to the world of ultra-fast HyperStar imaging, and I can tell you, it was a great relief! So far we have had a terrible summer weather-wise in the U.K., so I have only managed to take three further images since that first light image, including this latest one of the Coathanger Cluster shown in Image 7 on page 40. Taken on the July 27 2008, this used the amazing MicroTouch focuser which really takes the pain out of finding focus with low f-number systems. This image is only composed of 71 subs at 2-minutes per sub, yet the extremely faint reflection nebula LBN 130 can be seen lying just above the Coathanger. I should point out that the depth of focus with my setup is somewhere between 7 and 8 microns, where the diameter of a
DEEP-SKY IMAGING WITH STARIZONA’S HYPERSTAR human hair is around 80 microns. So, you are trying to position a large, heavy, 11-inch diameter mirror to an accuracy approaching one-tenth the diameter of a human hair. Doing this manually with an electric focuser is an extremely frustrating business. Clicking on an icon and seeing the focus lock into an FWHM of 1.3 after just a few seconds is great fun! I am now really pleased to have a finely-tuned HyperStar imaging system at the New Forest Observatory once again, and I will keep this particular setup for a very long time to come. But is there anything that can be done to improve the HyperStar system still further? I think there are a couple of things that will make the HyperStar perfect, for me at least. Firstly, it would be nice to be able to change the 2-inch filter through a slot in the side of the adapter nose piece. This way you could change filters without having to remove the CCD camera and break into the optical train. I believe Dean already has this small design change under consideration. The second change I’d like to see is the HyperStar
made to accommodate a full 35-mm sized CCD – but then again, deep-sky imagers always want more and more, and it might be physically impossible (I don’t know) to fit a 35-mm sized CCD to an 11-inch diameter f/2 system using a HyperStar lens assembly. There is a book explaining how I took all the original HyperStar images and the system tweaks I used to bring the best out of the setup called Making Beautiful Deep-Sky Images. It is part of the Patrick Moore “Practi-
cal Astronomy” series published by Springer and is available through Starizona. A second book will be published by Springer in January 2009. This is a large format coffee-table book of HyperStar and Sky 90 deep-sky images called Star Vistas, (www.starvistas.com) with Forewords by Sir Arthur C. Clarke, Sir Patrick Moore and Dr. Brian May. This is a “pretty picture” book, pure and simple. Until next time, I wish you all clear skies and happy imaging.
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Image 2
Image 5
Image 6
Image 7 Image 3
Image 4
Image 2 – A 4-frame HyperStar Mosaic of the Pleaides Image 3 – A 3-frame HyperStar Mosaic of the Horsehead Region Image 4 – M31 Using the Sky 90/M25C Image 5 – The Veil Nebula Using the Sky 90/M25C Image 6 – First Light for the HyperStar III at the NFO Image 7 – The Coathanger Cluster Courtesy of the HyperStar III
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The ScopeStuff EbonyStar Laminate Round-Bearing Kit An Easy Upgrade to Budget Dobs By Jason Scherff
You wanted a lot of bang for the buck. You only had so much cash. You had a need for aperture. So, of course you bought one of the many available imported Dobsonians that comes with an “O”, “M”, “C”, or even some lesser known moniker. No worries, so did I. And why not?! The performance-tovalue ratio of these now common 8-, 10-, and 12-inch instruments is unfathomable from a vantage point some 30 years ago, back when a 6-inch Newtonian was actually considered big. My own venture began upon receiving my 12-inch f/5 Dob via parcel service a few years ago. The two-box kit was easy to assemble, and by nightfall I was enjoying views of M31, the Double Cluster, and the lunar surface, on an entirely different level than my 4.5-inch Newtonian could ever provide. Galactic dust lanes were visible, stars produced colors, and tiny craters were now...no longer tiny! The large white tube, together with the scope’s shark-like appetite, earned it the nickname “Great White.” During this session I took notice of
the movements of the rocker box. Optics are, of course, important. But so are the mechanics. Without a smooth, sturdy mount, what good are fine optics? The altitude bearings were seemingly smooth and strong enough, while sitting atop small PTFE pads. Unfortunately, I was immediately struck with the overly free moving, slightly unstable azimuth bearing. It became apparent to me that the small, one-piece plastic ring, with diminutive built-in cylindrical bearings, was just not enough to handle the demands of a 65-pound optical tube assembly (OTA), plus rocker box. Over the next few years I tried to improve the movements using various methods I had read about on astronomy forums. One fix suggested using the “fuzzy” side of self-adhesive Velcro tabs between the ground board and rocker box, to soften and slow the movement. This did make panning the scope easier. But it didn’t eliminate the wobbliness of the OTA that I encountered at higher magnifications. Then, frustration ensued when the tabs eventually caught and
folded between the layers under repeated use, revealing the adhesive, and dragging “goo” between the ground board and box. Yuk! The next fix entailed completely removing the plastic azimuth bearing ring and small pivot bolt, and replacing the entire setup with an all-steel Lazy Susan bearing. This was a big improvement in stability and smoothness. But the bearing was so free of friction, that any slight bump or tap of the OTA would knock the scope off course. Adding some stapled felt pads (no adhesives this time) helped counter this loose movement. The real problem was that over time the smoothness disappeared, possibly from sand and dirt, possibly from repeated use. Either way, it was very frustrating. Then one day, by chance, I read about these marvelously simple azimuth bearing kits from ScopeStuff using PTFE and laminate. The concept seemed to replicate the design being used on premium truss Dobs. Available as direct replacements for the various imported Astronomy TECHNOLOGY TODAY
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THE SCOPESTUFF EBONYSTAR LAMINATE ROUND-BEARING KIT Dobs, and precut to size, I figured I couldn’t go wrong. So, I immediately ordered one for “Great White.” The $59 package, listed as #LD24 (specific for 12-inch Dobs) on the ScopeStuff website (www.scopestuff.com), included one laminate ring bearing cut to the size of my ground board, and three 1-inch square PTFE pads with retainers to keep them in place during azimuth movement. Kits range in price from $59 down to $42 for the various intended scope sizes. Assembly was straightforward and detailed instructions can be found on the ScopeStuff website for further reference. Using a high-contact adhesive, I centered The precision-cut bearing kit components and placed the laminate ring on the ready for installation underside of the rocker box. I then measured the distance of the ring from center and matched the measurement for the placement of the PTFE squares and retaining guides on the top side of the ground board. After marking the placement of the Contact adhesive is applied to the laminate ring retainers, I adhered them using the same method as the ring. Once dry, the PTFE pads can be dropped in before reconnecting the box to the ground board via the original pivot bolt. There are ways to adhere PTFE (the latest version uses recessed screws), but I chose to leave the pads free floating, since my pivot bolt is tight enough to clamp the two layers without allowing the pads to escape. A consideration for the thickness of the pads had to be made by adding a bushing (washer) of equal thickness to the pivot bolt between the rocker box and ground board. Doing The positions of the retaining guides are this will help to prevent warping of the marked on the ground board
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Astronomy TECHNOLOGY TODAY
THE SCOPESTUFF EBONYSTAR LAMINATE ROUND-BEARING KIT feeling of the scope when rotated on axis was now extraordinary in comparison. A quick trip to the backyard observing platform found Saturn in perfect position for testing. I was simply astonished as to how smooth, yet controlled, the hand The small, stock pivot bolt was replaced with a section of 1-inch tracking movement I.D. aluminum tube mated to a bolt/nut of equal O.D. was. With a firm, yet gentle pressure, the OTA can be slewed from a standstill position without any jerkiness whatsoever. Although there is now a small amount of effort required to move the scope at the azimuth axis, the contacts produce just the right The reassembled base is much more stable amount of friction to prevent the tarfiberboard, and retain a smoother long get from escaping the field of view due to term movement. simple knocks and bumps. In addition to the azimuth bearing The overall design is nothing new to kit upgrade, I decided to improve the the custom Dob world. But having a kit small pivot bolt that came with the scope that brings such a level of quality to the as original equipment. The design is hard mass market segment is a great idea. to beat, but the size of the original hardInitially, the price for a few small pieces of ware is well under proportion to the precut common materials might seem a bit weight of the scope. So I cut a small piece much, but once used in the field, that price of aluminum tube with a 1-inch inner is all but forgotten. Three months and sevdiameter and mated it to a bolt/nut eral observing sessions have passed since combo of equal diameter. This is more the upgrade. So slick, so sturdy, it makes than twice the width of the stock pivot the whole instrument feel like it’s of signifbolt, and inconceivably stronger. icantly higher quality. Once fully reassembled, the scope This may very well be the best had an immediate improvement in rigidupgrade I’ve ever done to “Great White.” ity. Gone was the flimsy feeling that once And now, just maybe, the name “Great” plagued this budget DSO hunter. The will finally apply.
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The Virtual Observer A New Breakthrough Technology for the Visual Observer - Part 2 By Roger Blake
Part 1 of this article appeared last month. In it I introduced the Virtual Observer (VO), a new and unique computer simulator that provides definitive and quantitative, answers to the most fundamental questions about telescopes and visual observing: “What can I see?” “How well can I see it?” and “What equipment do I need?” I want to stress the point that this is a unique research tool, based on published research, with a totally new capability that has never been available until now! It is a computer simulator of visual telescope observations. The VO traces the light from a celestial object, through the atmosphere, through the telescope and eyepiece, and then into the eye. But that is the easy part. At its heart, VO also has a human model component that evaluates how the mind “interprets” the light that falls on the retina in terms of actual image visibility. VO not only actually tells us if we can “see” the object, but also how well! As noted in Part 1, the human model is based on the report of definitive research work performed by H. Richard Blackwell, entitled “Contrast Thresholds of the Human Eye,” and published in the Journal of the Optical Society of America, Volume 36, Number 11, November 1946. At this phase of development, the VO quantifies visibility in terms of a number called the “Visibility Index.” The index values range
from 0 to 1 (approximately). Values near 0 mean that the mind will not “see” the object. Values near 1 mean that the mental image will appear photo-like. Last month, in Part 1, I used VO to analyze the effect of magnification and telescope size on the visibility of M97, the Owl Nebula. I also put out a call for help to any observers who would like to participate in the final phase of the VO model research and development by making a few simple observations. This month, in Part 2, I will extend the application of VO to study the effects of eyepupil diameter (age), telescope aperture, and light pollution. I will also make some direct comparisons of the VO model predictions to actual observations. And finally, I’ll provide more information about my call for research help. If time and space permit, future articles may address other observational issues and study results. I’ll begin with an actual observational example of the application of the VO model. This will provide an opportunity to review the key results from Part 1, and leads into the Part 2 objectives. Earlier this year, I made two sets of observations of M97. In both sets, I documented the observational conditions and descriptions of what I saw in the eyepiece. Later, I ran VO cases to simulate these conditions and then compared the VO visibility predictions to my actual observations. As you will see, I would have been better off to have run
VO first, before I made the observations, because it told me something that would have been helpful. The first observation was made under a clear sky with average transparency and a moderate light pollution level of 19.04 magnitudes per square arc-second (msa). The second observation was made under nearly identical conditions a few weeks later. The primary change was that I moved to a darker location. My observation notes are shown below. Observation #1 Notes: Target: M97 Telescope: 10-inch f/5 Eyepieces: 12.5 mm (100x), 25 mm ( 50x) Filters: None Eye pupil diameter: 3.5 mm Sky brightness: 19.04 msa Averted Vision: Barely visible, and only with motion. Just a vague hazy patch, no boundaries, no structure. Direct Vision: Not detectable Observation #2 Notes: Same as #1 except: Sky brightness: 20.25 msa Averted Vision: Easy to spot. I can see the whole object, but no detail, edge is fuzzy. Direct Vision: almost disappears, but I can barely see something. A few months later, I simulated both
Astronomy TECHNOLOGY TODAY
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and noted then that the existence of such a observations with the VO computer model. sharp peak was a surprise to me. There is more The results are shown, opposite page, in to say about this peak and I’ll get back to it a Figure 1 and Figure 2. little later. These figures are very similar to those As described in my observation notes, I shown last month, in Part 1 of this article. observed M97 at 50x and 100x magnification. They show the VO model predictions of the The predicted visibility at these magnifications visibility of M97 for a range of telescope magis shown in the figures with circles. Notice that nifications. The red line represents the visibilusing these two magnifications caused me to ity using “averted” vision and the blue line miss the predicted peak visibility at 72x. If I’d represents “direct” vision. Figure 1 is the preknown this before the observation, I would diction for the specific conditions of Observahave made an additional observation with an tion 1, and Figure 2 for Observation 2. 18-mm eyepiece, at about 71x. The shape of the lines in both figures is Now let’s compare the VO model preessentially identical. The difference is that the dictions in Figures 1 and 2, to my actual obFigure 2 lines are shifted upward, indicating servations as shown in Table 1. “Obs” is the better visibility relative to Figure 1. This is the observation number, and “Max VO” is the effect of the darker sky in Observation 2. maximum of the two visibility index values at Both blue lines also show a sharp peak, with visibility falling off rapidly Table 1: Actual Observations at both lower and Obs Vision Max VO Notes higher magnifica- 1 Averted +.23 Barely Visible tions. Last month 1 Direct -.10 Not Visible I referred to these 2 Averted +.52 Easy to Spot peaks as “cusps” 2 Direct +.12 Barely, Only Partially Visible
THE VIRTUAL OBSERVER 50x and 100x, as read from Figure 1 and 2. The agreement is good. As the predicted visibility index increases from -.10 to .52; the observation notes describe a real, corresponding increase in the actual visibility from “not visible” to “easy to spot.” This is encouraging (but not conclusive) evidence that the VO model represents reality. This is also a good illustration of my request for help from readers. Ideally, many different readers would make simple, but careful observations, document the results to me, and then I would run the VO model and make comparisons much like my example above. This effort would have two objectives. First it would provide a basis for judging the VO capability, and second, it might enable the calibration of the visibility index against actual visual images. Now let me return to the “cusp” or sharp peak in the “Direct Vision” line that I mention above. The presence and location of this peak is somewhat of a contradiction to the conventional wisdom that I’ve been exposed to during the 30 plus years that I’ve been in this hobby. So I want to provide a more detailed explanation of what the cusp represents and then compare it to conventional wisdom. The cusp is a common feature in all direct vision visibility lines and it always occurs at exactly the Minimum Useable Magnification (MUM). The value of the MUM varies for each observer and telescope combination. You can calculate your MUM by dividing the diameter of your telescope by your eye pupil diameter (both in the same units). A plot of typical eye pupil diameter versus age is provided in Figure 3. In my observations, my clear aperture was 10 inches, which is 254 mm, and my pupil diameter was 3.5 mm. Therefore, my MUM for these observations is 254/3.5 = 72.6x, exactly where VO calculated the peak. Now, the VO model doesn’t know anything about the MUM per se; it simply calculates visibility based optical physics and the human model component, which is based on the Blackwell research described last month. So what does the term Minimum Useable Magnification (MUM) mean? Well, it describes a characteristic of the telescope and human combination that may be unfamiliar to readers. I’ll explain using what I hope will be Astronomy TECHNOLOGY TODAY
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a relatively simple and intuitive example. An observer views M97, the Owl Nebula with a telescope. Three facts should be obvious. (1) The total amount of light that forms the image of M97 on the retina of the observer’s eye was captured by the clear aperture of the telescope. (2) The image of M97 on the retina gets bigger, or smaller, depending on the telescope magnification used. But the total amount of light from M97 captured by the telescope remains constant. (3) It therefore follows that as the image gets bigger, it must also get dimmer because the same amount of light is spread over a larger image. So, as magnification goes up, the object appears bigger and dimmer. Conversely, the object appears smaller and brighter as magnification is reduced. So far, this is probably obvious to most observers. The maybe not-so-obvious part is that when the magnification is reduced to the MUM value, the object brightness no longer increases with further reductions in magnification! At magnifications below the MUM, the object continues to decrease in size, but the brightness on the retina of the observer remains constant! Why?
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The reason is fairly simple. The light shaft that leaves the eyepiece on its way to the eye has a diameter called the “exit pupil.” As the magnification is reduced, this diameter gets bigger. At magnifications greater than the MUM, the diameter of the exit pupil is always smaller than the eye pupil, and all light transferred by the telescope gets into the eye. At the MUM, the diameter of the exit pupil is exactly equal to the diameter of the eye pupil. Further reduction in magnification causes the exit pupil diameter to exceed that of the eye pupil, causing a partial loss of light. This happens in such a way that the surface brightness of the image on the retina remains constant for all magnifications below the MUM. OK, so what is the conventional wisdom? You usually find it stated something like this, “It is well known that objects are brightest at the MUM condition, but it is a fallacy commonly committed by newbie’s that this is the best magnification for visual observing. The best visibility occurs at higher magnifications.” Now, the truth is that this is partially right…and partially wrong. Part of the confusion is caused by not being specific with re-
gard to averted versus direct vision. The above conventional wisdom is often, but not always, true for averted vision. This was demonstrated in all the VO plots and conclusions shown last month. Note also that it is only barely true in Figure 1 and completely untrue for Figure 2. But conventional wisdom is always false for direct vision, for which the brightest magnification will always be exactly the MUM, as described above. Now I’ll move on and apply the VO to investigate three important issues that effect how well visual observers can “see” dim, deep space objects: (1) What is the effect of the reduction in eye pupil diameter with age? (2) What is the effect of telescope aperture? (3) What is the effect of light pollution? As shown in Figure 3, eye pupil diameter decreases almost linearly with age. As discussed above, one effect of this is the change in the MUM value which defines the optimum magnification. But what is the net effect on a visual observer’s ability to see deep space objects like M97? This is exactly the type of question that the VO model is designed to answer! We simply simulate different observers with various pupil diameters and see what trends VO predicts in the values of the visibility index. To make it simple, we’ll choose some typical values for the other key parameters such as telescope size, sky brightness and the others. The VO results are shown in Figure 4. To make it more meaningful, I’ve converted from pupil diameter to age using Figure 3. The red and blue lines represent the averted and direct vision results respectively. They represent the VO prediction of the net effect of the reduction in pupil diameter on a typical observer’s ability to “see” M97. Now these lines would have been higher or lower if the analysis had been done with a different size telescope, or a different light-pollution condition, but what is important is the change in the visibility over time. At age 25, the visibility as depicted by the blue line is about 0.37. At age 70, this decreases to about 0.24. This is a decrease of about 0.13, or about 13% of the full visibility scale of 0 to 1. Now to the red line. This is an amazing result! It says that the entire range of reduction
THE VIRTUAL OBSERVER in pupil size has absolutely no adverse effect on the averted vision! How can this be true? I spent a considerable amount of time looking for a bug in the VO model, trying to find the cause of this crazy result! But I soon came to the realization that, again, the VO model had shown me another truth about visual observing that I never suspected in the 30+ years in this hobby! So let me explain why, after some thought, it became obvious that VO was correct. Look back at the red line (averted vision) in Figure 1. Recall the discussion earlier in this article about the Minimum Useable Magnification, or MUM, as it applied to the peak, or cusp, in the blue line. Note that in Figure 1, there is a similar “corner-like� feature in the red line at the MUM (in this case at 72x). The cause is the same. Above the MUM, the diameter of light-shaft leaving the eyepiece, called the exit pupil, is always smaller than the diameter of the eye pupil and all the light gets into the eye. Below the MUM there is a partial light cutoff. Now combine this with the conclusion mentioned earlier, that the optimum magnifi-
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Table 2: Affect of Changing Aperture on Visibility Change In Aperture 4 to 6 in. 6 to 8 in. 8 to 12 in 12 to 16 in. 16 to 20 in 20 to 24 in.
Averted Vision Gain % 17.3 2.1 14.1 9.3 6.0 5.2
cation for averted vision is always equal to, and frequently greater than, the MUM. Combining these two, we see that the optimum view for averted vision always occurs at magnifications above the MUM, when the exit pupil is smaller than the eye pupil, and therefore, the diameter of the eye pupil never has any affect on averted vision! Next, the analysis of telescope aperture (diameter). An observer often ponders the question of how big a telescope to buy. It’s a question of budget versus performance. For visual observing, performance often means the ability to see dim, deep space objects. Until now, there has been no quantitative way to evaluate this performance question. But
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Direct Vision Gain % 17.8 9.1 10.0 3.9 1.2 0.7
now VO can answer this question definitively. Just choose the telescope, target, and observing conditions and VO will provide a numerical value of the visibility. Compare the visibilities for a range of telescopes and targets and then choose the results that fit your needs. A comprehensive analysis of aperture would include many targets, under a range of observing conditions. A much simplified analysis is presented here, using only M97 as the target, with relatively dark skies of 20.5 msa, a middle-aged observer with 5-mm pupils, under typical atmospheric conditions. M97 itself is a good choice because its size and surface brightness are typical of many of the popular galaxies and nebulae. The sky
brightness is typical of a good observing site, but is significantly darker than the back yards of 99 percent of the population. The results of the aperture analysis are shown in Figure 5. For both averted and direct vision, the increase in visibility becomes less and less with increased aperture. I refer to this as a “saturation” effect. I’ve noted in the figure the effect of doubling the telescope aperture from 8 inches to 16 inches. The observer would gain 0.14 in direct vision and 0.23 in averted vision, or 14% and 23% respectively of the full visibility scale. Using the same technique, the reader can verify the gains for the other increments shown in Table 2. The results in Table 2 demonstrate that adding 2 inches of aperture, going from a 4inch telescope to a 6-inch one, provides a dramatic change of more that 17%. Increasing another 2 inches, from 6 to 8 inches, provides significantly less benefit, only 12% and 9%. Doubling the increment to 4 inches, from 8 to 12 inches, gets another 14% and 10%. The benefits are even smaller for the larger scopes. The reader should keep in mind that these results are for M97. Brighter objects like M51 will have a different set of visibility curves. In particular, the direct vision line reaches significant visibility levels. Now let’s turn to the last analysis, and answer the question, “What is the net effect of light pollution on a visual observer’s ability to see deep space objects like M97?” Again we run VO computer simulation cases in which we vary one parameter, in this case sky brightness, while holding everything else constant, and see what trends VO predicts in the values of the visibility index. Again, to make it simple, we’ll choose some typical values for the other key parameters and use M97 as the target. The results are shown in Figure 6. The range of sky brightness shown is from 19.0 to 22.0 magnitudes per square arc-second (msa). 19.0 msa is a moderately dark location. Most of the people in the U.S. live under skies that are brighter than 19.0 msa, and 22.0 msa is as dark as it gets anywhere. The trend lines are nearly straight, with both averted and direct vision increasing by about 60 percent over the entire range. I have
THE VIRTUAL OBSERVER annotated on the map the effect of moving only 1 msa, which provides a 20% benefit. In most cases, one can find a 1 msa darker location within 10-20 miles. What is striking about Figure 6 is that the benefit gained by moving to a 1 msa darker location is almost a constant 20% improvement in visibility, regardless how dark the starting point is (up to a max of 22.0). Everyone can tell the difference between 18 msa (urban) skies and 19 msa, but fewer can readily detect the difference from 19 to 20, 20 to 21, etc. This creates a dual pitfall. First, an observer may not have been aware, until now, how much benefit could result from a darker site, and second, how to find a darker site, since they are not visually very obvious. The answer is to use light pollution maps. First, find out how dark your site really is and then look around for darker locations close by. You can use the web based maps associated with the Clear Sky Clock, or you can consider using my PC-based maps, the Dark Sky Atlas. You can download a free demo version at http://www.taurus-tech.com/dsa_demo.htm. Finally I return to my call for help from readers to make some simple observations and report the results to me for comparison to the VO model. A full range of observers and telescopes are needed. Please visit www.taurus-tech.com for details. I have posted a list of targets, with photos, and the dates and time of observation windows to avoid the moon, and twilight conditions. I’ve also included sample data sheets listing the key information to be recorded and samples of visibility descriptions. VO Project pamphlets will also be distributed and project activities organized by a number of star parties scheduled for fall and winter of 2008, so please ask your star party organizers for a copy. All contributors will be acknowledged in the final, publicly released, research report. This report will document the results of the comparisons of the observations to the VO model predictions and contributors will receive a free copy. In the end, I sincerely hope that the VO project will result in a tool that will be of significant aid in optimizing your visual observing experiences.
SUMMARY OF VISIBILITY RESULTS FOR M97 1. Vision - deep space observers use two types of vision: direct vision and averted vision (refer to discussion in the earlier VO article Part I). Averted vision is 20-40% more sensitive than direct vision (compare red and blue curves in figures) , but is much less satisfying because you can’t really see as much detail with peripheral vision. 2. Magnification - For Direct Vision, there is only one “best” magnification, The MUM (Minimum Useable Magnification). MUM = Scope Diameter /Eye Pupil Diameter. Visibility falls off rapidly above and below this magnification. For Averted Vision, visibility falls off rapidly below the MUM, and the optimum magnification usually falls between the MUM and 2x MUM 3. Eye Pupil Diameter - Typical eye pupil diameter vs. age is shown in Figure 3. For direct vision, an observer loses about 13% visibility over 45 years. For averted vision, the reduction in eye pupil diameter has no effect. 4. Telescope Aperture - As expected, visibility increases with increases in the telescope clear aperture. The gain is not linear. In my observations of M97, the greatest gain occurs for small telescopes, and reduces drastically with larger telescopes. Doubling the aperture from 8 in. to 16 in. provides a 23% gain in averted vision, but only a 14% gain in direct vision. Refer to Figure 5 and Table 2. 5. Light Pollution - Light pollution is the biggest cause of telescope blindness, Moving 10-20 miles to a darker observing site can have the same benefit as doubling your telescope aperture. 6. Test Results - Limited comparison of actual observations to VO visibility predictions has shown good agreement. More comparisons are needed.
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The Orion Sirius EQ-G Mount and StarShoot AutoGuider Taking a Long Ride with the Sirius EQ-G and SSAG By Dave Snay
Along with the Orion StarShoot Deep Space Monochrome Imager and Newtonian combination, which I described in the August issue of ATT, I also tested one of their Sirius EQ-G mounts and a StarShoot AutoGuider for the project. Because I felt that these were so integral to the setup and played such a large part of the success of that project, I decided to write a separate article detailing the support system for the Orion imaging tools. Although some may be surprised by this, I had never before used a motorized German Equatorial Mount (GEM) until this project. This was one of my more educational (for me) excursions. My previous astro-imaging experience was with fork and equatorial-wedge mounted Schmidt Cassegrain telescopes (SCTs) and piggybacked refractors. As a retired engineer, I am used to learning new things and usually
jump at the chance for new data. So let’s go see what I learned. As you’ll notice, I made my share of mistakes along the way, but the Sirius EQG and StarShoot AutoGuider (SSAG) never let me down. I’m sure the folks at Orion thought I was suffering from “User Brain Damage” at times, but they were right on the spot with quick, helpful answers and the occasional, gentle reminder that many of the answers were also in the manuals provided with the equipment.
gust article, I also used one of Orion’s ST80s to use as a guide scope for this project), and one for the mount and the rail to hold the tube rings for the Newtonian. Everything arrived extremely well packed and showed no signs of damage, despite the deliveryman’s best efforts to kick it around on the way to my house. Can someone explain to me why the words “Fragile, Do Not Drop” have no meaning to the delivery companies?
What’s in the box? This portion of the original shipment came to me in three boxes: one for the tripod and spreader, which serves to hold the mount to the head of the tripod, one for the SSAG, Hand Controller and rail for the guide scope (in case you didn’t catch my Au-
Fit and Finish The Sirius EQ-G mount looks and feels very well made. Both axes move smoothly and easily, while the lock-down levers apply increasing pressure until the axes are fully locked. When fully locked down, each axis will still move if the scope Astronomy TECHNOLOGY TODAY
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THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER is bumped sharply. This will throw off any previous alignment, but eliminates risk of damage to components, a feature that may be critical if the mount is used at crowded star parties. The finish on the mount also looks and feels well applied. All lines are clean, smooth and look very professional. In the time I’ve had the mount in my possession I noticed no marring of the finish, regardless of how many times I set up and tore down the system. I even carted the whole rig to the annual Summer Star Party hosted by the Rockland Astronomy Club and used it there for a week without any sign of wear to the mount. The SSAG is also well constructed. It is very lightweight – something I greatly appreciate. The connections for the USB cable and guide cables are directly on the back of the camera and provide solid feedback to indicate positive connection. You won’t be left in the dark wondering if you’ve got everything connected properly.
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Let’s Get Sirius My first impression of the mount was something like, “Wow, this thing is a lot heavier than I thought it would be!” It exudes strength, making me wonder just how much weight I could force it to carry before it cried “Uncle.” Despite loading it with lots of robust imaging equipment, I failed to find the limits of this mount. The Sirius EQ-G didn’t even notice when I added about four pounds to the load by swapping my much heavier refractor for the ST80 I’d been using as a guide scope. The tripod is of standard design. It does not have spreaders near the bottom of the tripod legs as others I have used, but it does not seem to suffer support. The presence of lower spreaders would make it easier to ensure that the legs are evenly spread, but the upper spreader that is supplied accomplishes that a little later in the setup process. The legs are of stainless steel construction with two telescoping segments each providing a wide range of height adjustment. The connections between the segments are
durable cast aluminum and should last the life of the mount. The mount itself attaches easily to the head of the tripod. There is a key mechanism that ensures the mount will only attach in the correct orientation. A single center bolt holds the mount down securely. Unlike typical SCT mount systems, the bolt does not permanently protrude through the tripod head, so there is no damage done to the base during installation. You simply place the mount on the tripod and then screw the bolt up into the base. This bolt also holds the spreader, which contacts each leg and stabilize the entire base. There is a slot in the spreader where you store the Orion hand controller when not in use. The holder feels much more solid than others which I have broken by over tightening the mounting bolt. The counterweights attach to a retractable rod that extends from the base of the mount with the simple release of a locking lever. Unscrew a thumbscrew at the end of the rod, slip on the counterweight(s) and
THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER reinstall the screw. I love that the manual appropriately refers to this thumbscrew as the “Toe Saver,” since having an 11-pound weight drop off the rod onto your toe would certainly put an end to the night. The Sirius EQ-G accepts a standard Vixen-style dovetail rail. My setup came complete with one rail to hold the Newtonian and another to mount on top of the Newt to hold the rings for the guide scope. I installed the rings for the Newt on the primary rail and installed that onto the mount. Then I attached the guide-scope rings on the smaller rail and attached that to the top of the primary rings. Next, I installed the Newtonian into its rings and the guide scope into the smaller set of rings. At that point, I was ready to go. The only improvement I would like to see in this setup is longer thumbscrews on the main tube rings. The standard ones are a little short so I couldn’t tighten or loosen them as easily as I would have liked. Since that first night, the typical disassembly I performed was to remove the weights and imagers. I’d leave the two scopes on the mount, pick it up easily, and then move into my storage area when I was done for the night and wasn’t going to be using it again for a few days due to weather. If the weather pattern was for several clear nights, then I’d just remove the imagers and cover the whole thing with a heavy-duty cover from TeleGizmo so I could be ready to go in a moment’s notice the next night. I did disassemble the entire setup a few times to alter the configuration as well as when I took it all to the Summer Star Party, but that experi-
ence only served to showed me just how easy it was to take it down and put it back up. The Sirius EQ-G mount comes with a 12-volt power cord that you can use to connect to a 12-volt DC power supply. Orion also produces an AC adapter that can be used to connect the mount to an AC power source if you’re in an observatory or have access at your observing site. You can also connect the hand controller directly to a power source to update the firmware without need to have the mount present. This is pure brilliance! Now I can update the firmware using only my PC, the hand controller and the Internet. My other telescope requires that the entire system be present so that I can power the hand controller via the telescope. Maintaining Control The buttons on the hand controller are grouped into four categories: Mode, Directional, Scroll and Dual Purpose. Each category is described in the manual, so I won’t go into the details here. However, the Dual Purpose buttons warrant special attention. The buttons that are numbered “1” through “9” are used as numbers when entering data. However, once you’ve got the system up and running, these buttons can be used to jump directly to one of the object categories supported by the hand controller. This makes the process of moving from object to object incredibly easy. You no longer need to navigate through menus if you want to move from M13 to NGC7000 to a User Defined object to one of the Utility functions. That’s very cool!
Speaking of object catalogs, the Orion hand controller supports Messier, NGC and IC catalogs as well as Planets. You can also enter objects by specifying the RA/Dec coordinates and saving the object in the User Defined catalog. The objects in the User Defined catalog are stored by index number only. You can’t save any text with the object, so you’ll have to remember which object is associated with each number so you can access them later. Changing the slew rate of the mount is also very simple. You simply press the RATE button and enter a number from one through nine for the desired rate, where “1” is slowest and “9” is highest. Press ENTER and the rate is now set. Unfortunately, the slew rate returns to the system’s default value between go-to movements, so you’ll have to reset the rate if you want to move the telescope using the hand controller at anything other than the default rate. There are several functions available in the Utility menu. However, the three I used the most are Park, PAE (see the next section
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THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER
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www.deepskyinstruments.com 58 Astronomy TECHNOLOGY TODAY
for details) and Temperature. Park returns the mount to the home position, saving all alignment, PEC, and PAE data so you can start up quickly and easily next time. The Temperature function simply displays the current ambient temperature. I find it useful when imaging to know the current temperature for a variety of reasons and this function provides that data without the need to carry a thermometer (ever try to read an anolog thermometer in the dark?). Pointing Accuracy Enhancement The Orion hand controller provides Pointing Accuracy Enhancement (PAE). This serves to fine tune the alignment of the mount in a specific area of the sky. To use PAE all you need to do is press and release the ESC button and then lean on the ESC button for two more seconds. You’ll be prompted to center the current object. Do that and press ENTER and you’re done. This will improve the go-to accuracy of the mount in that area of the sky. My testing showed a noticeable improvement. Before PAE, all objects showed up in the view of my 20-mm eyepiece in the primary scope. After PAE, those same objects showed up either dead center or nearly dead center in that 20-mm eyepiece. If you move to another area of the sky, your performance should still be very good. You can perform another iteration of PAE in that area to improve performance even further. If you park the scope, the hand controller remembers the PAE information for next time. Performing PAE on multiple wellknown stars in the same area of the sky provides further improvement of the system’s go-to accuracy. When I first tested this feature, I hadn’t used the scope in quite a while due to weather. During that time, one of the stars I had been using for alignment had shifted to nearly directly overhead. I’ve been at this long enough to know that any star at or near zenith is not a good alignment star, but I forgot that fact on the first night of PAE testing. My go-to performance was
THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER awful and no amount of PAE was able to correct the situation. I realized my mistake, performed a new alignment using stars approximately 45 degrees above the horizon and started again. After that, everything worked much better. I have to admit that I felt foolish after having spent the better part of two hours trying to figure out what was wrong with the mount only to discover it was pilot error. Things That Go Bump In the Night All gear-driven telescope mounts exhibit Periodic Error. Periodic Error is caused by inaccuracy of worm gear and/or stepper motors which move the mount in right ascension and declination. The shape of the gear has a pattern to it, which repeats on each revolution of the gear. Each revolution makes up one period. As the period repeats we see what has come be known as a bump in the tracking of the mount. This bump is not an issue for visual use. However, it can cause real problems for imaging if your exposures span that bump and the bump is relatively large. My fork/wedge mounted imaging setup has a big bump every nine minutes, so I have to make sure my exposures are shorter than that, which is not a problem since guiding a shaky mount like my tired old wedge limits me to about twoto three-minute exposures. The Orion hand controller firmware provides a tool for Periodic Error Correction, which involves measuring the existing error and letting the firmware calculate how to best compensate for it. I was planning to learn about how to use Periodic Error Correction to improve the tracking of a mount as part of this project. However, I eventually concluded that it is not necessary with this mount. Apparently, the stepper motors in the Sirius, and Atlas, mounts take very small steps, reducing the number of gears required between the rotor and the output shaft, making for much less of a bump in the night. Thanks to that enhancement, I can easily take 10minute exposures when guiding with the
StarShoot AutoGuider with no measurable distortion in the stars. On very good nights, I can go as long as 15-minute exposures. Given those accomplishments, I say, “Why bother with PEC?” I know I will never be able to take advantage of longer exposures than that from my light polluted location. I have also seen very different opinions on the usefulness of PEC if you are going to be guiding during exposures. Some tell me that PEC and guiding can work well together and others tell me that they will fight with each other in their attempts to correct the mount’s tracking. Personally, I don’t see how the two can work together without some very complicated software to integrate both sets of data. Remote Control The Orion hand controller provides an access port to use for linking to a computer for remote control from most planetary software. I decided to try connecting via RTGUI, which is freely available on the web. Until now, I have only used RTGUI
for helping choose objects for imaging. I followed the directions in the Sirius manual for connecting to the computer, started RTGUI, configured the program to recognize a Celestron NexStar 5i/8i (the manual recommends this), and specified the correct COM port. RTGUI doesn’t provide any indication of positive connect. It only tells you when it fails. I didn’t know that, so I was understandably unsure about success. However, when I selected an object from the interface and told the mount to slew to it, off it went. I was very happy to see things work with absolutely no intervention on my part. The less intervention from me, the higher the degree of success. I didn’t even need to install the ASCOM platform, which many more complex and fully-featured programs require. I love it when things are simple! I aligned the telescope and went about selecting objects from the search engine in RTGUI and slewing to them from the computer. The telescope responded as expected and found every object with the same accu-
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THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER racy as when specified from the hand controller. Given the ease of success using free software, it should be equally simple to achieve remote control of the Sirius EQ-G mount using any number of more sophisticated planetarium software packages. I used RTGUI to control the mount’s location before and after imaging sessions to see if there was any negative impact on the performance of either package. Not surprisingly, there was no visible effect on either the guiding or go-to accuracy, as long as I remembered to stop guiding prior to slewing to a new location. Slewing while guiding really confuses any guiding software! Keeping Up-to-Date The Orion hand controller software and database can be updated using software and data files from the Orion website. Documentation for the process can be found in the Sirius manual as well as on the website. I went through the process just to see how complex it is, and found it to be straight-
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forward. It turns out that you are not updating many items as the databases don’t change much. After all, the stars are pretty much where they were when the first databases were written. A Release Notes file describes the update contents. In this case, it was just a few minor corrections and an additional function in the Setup menu. The update process includes connecting the hand controller directly to the computer using the serial cable provided with the controller. My laptop doesn’t have a serial port, so I used a USB-serial converter for remote control of the mount. However, that did not work for me. The documentation indicates that a converter will work, but recommend a different converter than the one I have, so I probably just don’t have the right converter for the update program. I tried the update using my desktop computer, which has a serial port, and the update went smoothly and quickly. Because there is no support for customized tables in the databases, the update
process is very simple. There are no options to choose. You can update the firmware and databases and verify the versions in the hand controller. Alignment When using the Sirius EQ-G for visual observing, a rough polar alignment is all you need. Simply plop the tripod down with the leg labeled N pointing at Polaris, assemble the mount and scope, perform a simple one star alignment using the hand controller and you’re good to go. Objects will appear within the field of view of 20- to 30-mm eyepieces every time. Once you have done this level of alignment, objects will stay within the field of view indefinitely. You can perform PAE to fine tune things and your go-to movements will be more accurate. Further testing revealed the importance of your choice of alignment stars. If you choose stars that are not approximately 45 degrees above the horizon, your go-to performance will suffer. If you choose them well, go-to is more accurate. This is not unique to the Sirius mount. The same holds true for other mounts. If you are going to perform astrophotography or scientific measurements, then rough polar alignment will not be sufficient. You will need to be much more accurate. Fortunately, polar alignment of the Sirius EQ-G is very easy. It comes with an illuminated polar alignment scope in the mount, which I found very easy to use once I tried sitting on the ground. That puts me at exactly the right angle to peer through the alignment scope and see the alignment pattern while I adjust the mount. The manual provides thorough and easy to understand instructions for polar alignment. Follow the polar alignment process with a two or three star alignment using the hand controller and you will have your rig set for longer exposures. This is essential for imaging. It does not eliminate the need for auto-guiding, but it does make the job of guiding much easier and therefore much more successful.
THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER A Little Guidance Goes a Long Way The StarShoot AutoGuider (SSAG) could not be simpler to use. Have I mentioned how much I like things to be simple? Insert the SSAG in the guide scope, connect its USB cable to your computer, and the RJ12 cable to the guide port on the mount and you are ready to go. Fire up the PHD guiding software included with the SSAG, select a guide star and let the software do its thing. PHD will move the mount in all four cardinal directions to calibrate itself to the mount. There are many options within PHD to help you tailor its operation, but I found none of them necessary. I experimented with most of them and found that the SSAG/Sirius combination just plain worked without any assistance from me. In fact, once the system indicated that it was ready and guiding had started, it was as though the auto guider was not even there. It can take several minutes for PHD to complete the calibration task; longer exposures extend this time, but it is worth the
wait. The performance of the SSAG/Sirius/PHD combination is exceptional. It never lost the guide star (except for that one time I let the object disappear behind my house). Alignment of sub-exposures requires much less rotation, resulting in significantly less loss of data at the edges of the frames. As one of the more famous TV infomercials used to say, “Set it and forget it!” One note on the calibration process: if you are shooting at something near the Celestial North Pole, calibration will likely fail. It takes an awful lot of mount movement to make a guide star move enough to satisfy PHD’s rigorous calibration algorithm. It took me quite some time and more than one email exchange with the folks at Orion as well as with Craig Stark of Stark Labs (he wrote and distributes PHD) to realize what was happening. The work around is to slew the mount a little off the meridian and let PHD calibrate itself. Then slew to the intended target, disable the “force calibration” option in PHD, and start guiding. I found this to be very reliable when shooting any-
thing in the vicinity of Cassiopeia. Conclusions The Sirius EQ-G is one solid mount. This beast weighs in at 43 pounds, contributing greatly to its ability to carry the Newtonian, guide scope, auto guider and imager with no apparent stress. All moving parts look and feel strong enough for the job. Movements are smooth and free when locks are disengaged. During slews, the stepper motors sound very smooth and steady, although the motors sound very different when ending slews to a new target. At the end of the slew, they sound a little bit like the gears aren’t perfectly meshed. I put my hand on the mount during several slews to see if I could feel any change, but I felt none. It’s just the motors slowing down so that there is no whiplash within the motor housing. With even the most rudimentary polar alignment, go-to accuracy was sufficient to place any object in the field of a 26-mm eyepiece. With more accurate polar alignment
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THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER and a two-star hand-controller alignment, go-to accuracy improved noticeably. There was a brief period when I experienced what I thought was poor go-to accuracy. However, that turned out to be good old pilot error. I had switched out the Newtonian for my 80-mm refractor and neglected to verify that the telescope was well aligned with the mount. Inspection showed that the back end of the scope was significantly closer to the mounting rail than the front end. I learned that is what they mean by “Cone Error”, which wreaks havoc with pretty much everything. I straightened that out and everything returned to normal. As I mentioned earlier, the Sirius EQ-G tracks objects very well. I was able to achieve 45 second exposures with no guiding. Stacking them required more effort than guided images, but that effort was performed by software so I didn’t really notice it other than the loss of a little bit of image at the edges due to rotation. Put an auto guider like the SSAG in the mix and very long exposures are easy. I was able to achieve
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10-minute exposures with no problem and 15-minute exposures can be achieved with more careful polar alignment such as drift alignment after initial polar alignment. I have never used a guide scope that was not at least twice as long as the imaging scope, so I was a little apprehensive about the ability to guide with such a short scope as the ST80. However, the combination of the little 80 and the StarShoot AutoGuider did a wonderful job of keeping everything exactly where I wanted it. This changes everything about what I thought I needed for equipment to play in this wonderful hobby. I absolutely love the dual-purpose buttons on the hand controller. I have always had to meander through long menus trying to find the right category for the next object. These buttons make it a snap. Just hit the ESC button and then any one of the dual-purpose buttons and you’re in the category you want. You can go through the menus if you want, but why would you do that?
The Sirius EQ-G hand controller also provides the ability to adjust things like backlash compensation and auto-guide speed. I won’t go into the gory details of those here. However, their presence shows the dedication of the folks at Orion to provide us with a very nice mount that we can tweak to achieve the most accurate performance possible. As I mentioned at the start of this article, I have never owned an equatorial mount; I have always used an SCT on a wedge for imaging. Setting up the wedge and scope and then polar aligning that rig is not a quick process, but it is one I have gotten used to and can perform in about a 45 minutes. I thought that was pretty good. Then the Orion gear showed up on my door step. I can set this up from start to finish and be ready to start imaging in less than 20 minutes. It is less than that most nights because I never take the mount and scopes off the tripod. I just remove the counter weights and carry the whole shebang into my shed. I can’t do that with my wedge
THE ORION SIRIUS EQ-G MOUNT AND STARSHOOT AUTOGUIDER setup without risking injury. The biggest bonus for me is how much longer my exposures can be with this configuration. I can easily go 3 times as long with each exposure than I could with my standard wedge. I mentioned that I took the entire setup to the Rockland Astronomy Club’s Summer Star Party. The Summer Star Party is a 10day event where the club members and guests descend on Shady Pines Campground in Savoy, Massachusetts, and occupy the northern half of the property. It is quite a site to see more than 100 telescopes of all types and sizes arrayed on the field. While there, I demonstrated the system to many of the attendees and there were questions about virtually all parts of this setup. Some wanted to know about the accuracy of the mount. Some wanted to know about the Newtonian’s astro-photography optimizations. Others wanted to know all about the StarShoot Camera and AutoGuider. Suffice it say, I was a very busy guy while I was there. Everyone was aware that Orion produces some very nice ED refractors, and many of them had heard something of the effort put into producing high-quality mounts such as the Sirius and Atlas mounts. However, the Newtonian’s performance was quite a surprise to many people. I’m not sure why, but most of them did not expect the Newt to provide such nice data. The ability of the mount to carry the load impressed everyone who checked it out. At one point, I had the Newtonian and my own refractor, which is about twice the weight of the ST80, on the system and there was no sign of overload. Images through the eyepiece were steady and imaging performance was uncompromised. The Sirius EQ-G lists for $1149 US and the StarShoot AutoGuider lists for $249 US. Considering the versatility and accuracy of this package, it represents an exceptional value. If you are in the market for a new imaging platform, you should explore this combination. I was so impressed with this setup that I couldn't part with it. So I bought it and expect to be imaging and observing with it for years to come!
ORION SIRIUS EQ-G MOUNT SPECIFICATIONS Load Capacity...........................................................................30 Pounds Objects in Go-To Database................................................................13,436 Tracking Rates ......................................................Sidereal, Solar, and Lunar Slew Speeds ..................600, 500, 400, 64, 32, 16, 8, 2, 1.75, 1.5, and 1.25 times (Up to 3.4 Degrees Per Second) Motor Type ..........................................................Micro-Step Stepper Motors Bearing .....................................................................Sealed Ball Bearings Power Requirement ..........................................................12-Volt DC, 2 Amp PEC................................................................................................Yes GPS .........................................................................................Optional Backlash Compensation .......................................................................Yes Latitude Range...................................................................9 to 72 Degrees Setting Circles ..................................................................................Yes Polar-Axis Scope .........................................................................Included Counterweights ...........................................................One 11 Pound Weight Available Ports .............................................................RS-232, Auto Guider Tripod Leg Material ..........................................................................Steel Tripod Leg Diameter .................................................................1.75 Inches Counterweight Bar Length...............................................................8 Inches Diameter of Counterweight Shaft ........................................................18 mm Height Range of Mount/Tripod .................................................42 to 55 Inches
ORION STARSHOOT AUTOGUIDER SPECIFICATIONS Imaging Sensor ................................................................Micron MT9M001 Imaging Sensor Size .....................................................6.67 mm by 5.32 mm Pixel Array ......................................................1280 x 1024 (1,310,720 Total) Pixel Size ................................................................................5.2 by 5.2 Imaging Chip ........................................................................Monochrome Video Frame Rate .....................................15 Frames/Second at Full Resolution A/D Conversion ................................................................................8 Bit Mounting...........................................................1.25-inch Nozzle or T-thread USB Connection ..................................................................High-Speed 2.0 Software Compatibility ..............................................Windows XP/Vista 32-bit Weight.................................................................................4.40 Ounces
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ASTRO TIPS tips, tricks and novel solutions
Daisy, Daisy, give me the altitude...
By Rod Nabholz
“Red Dot” finders were designed as sights for firearms, but the astronomy community soon adopted them to its purposes. Here’s how to install one for under $10, including the cost of the finder! The main component is a Daisy Electronic Point Sight, available at most sporting goods and big discount stores, typically selling for less than $10 (I found mine
Submit Your Astro Tip! Astronomy Technology Today regularly features tips, tricks, and other novel solutions. To submit your tip, trick, or novel solution, email the following information: • A Microsoft Word document detailing your tip, trick or novel solution. • A hi-resolution digital image in jpeg format (if available). Please send your information to tips@astronomytechnologytoday.com
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for $7). Once you have the Daisy, here’s a way to mount it. As you can see, the components are pretty simple: two binder clips, two 3-inch #10 stove bolts, some nuts and lock washers, and a small block of metal known as a “machine key” (a small block of hardwood works just as well). Drill two holes in both binder clips along the topside, evenly spaced down the center line and just large enough for the bolt to slip through. Drilling the holes is easier if you clamp the clip on a narrow piece of 1/2-inch plywood or wood stock. Assembly is easy and detailed instructions are available for review online at http:// users.indytel.com/~rnabholz. I attached the length of machine key with strip of doublesided tape on the bottom of the key and, taking care to ensure that it is lined up well with the centerline of the tube, pressed it into place. The height provided by the 3-inch bolts moves the finder off of the tube to a position that is much easier to view through than if it was attached directly to the tube. This system
provides good repeatability – at least on par with other dot-type finders I have used. It takes just a small tweak to zero it in upon reinstalling it on the scope. If esthetics is of concern, this idea probably falls short. But for times when an inexpensive, easy solution is appropriate, this is a great one. Club scopes, Kid’s Scopes, Grab and Go’s, anywhere that cheap, quick and easy is the idea.
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