Astro Nerds Astronomy Ezine March 2015

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Welcome to March Edtion Of Astro Nerds Spring is beckoning, the days are getting longer, for some of us that is bad news, however spring and summer still brings us many delights in the night sky. We have are usual features this month, with the night sky, gallery and part 2 of astrophotography without a telescope. For those who are active on social media many would have seen the stunning images from Jaspal Chadha, he talks to us about his journey into astronomy, and we do include some of his stunning images. We have also updated the website with some new features and revamped older ones. The International Space Station (ISS) page has gone through improvements, with a live news feed, live video

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links and a location map via the ESA. A new feature on the website are news updates, articles and video


on Saturn’s moon , Titan. We are also at the starting point of a new project. The project is to bring a small public observatory to the Wolds of Yorkshire, check the website for details. Editor: David Bood

6. Solar filaments and prominences 18. PT 2 Astrophotography Without a Telescope 30. Look Up, A guide to the night sky 38. Reader Profile, Jaspal Chadha

ENJOY.... Astro Nerds March 2015


Solar filaments and prominences – by Andy Devey Filaments are large regions of very dense, cool gas, held in place by magnetic fields they are like curtains of suspended gas. They usually appear long and thin above the chromosphere. It is because they are cooler than their surroundings that they appear dark. But if they appear on the “edge” of the Sun, they appear brighter than the dark outer space behind them. In that case we call them prominences. Prominences and filaments are really the same thing, but they look bright or dark depending on what is in the picture’s background. Occasionally the Sun will treat us to some of these features that are monstrous in their dimensions. During February 2015 one such feature was over 1,000,000 km long a distance equivalent to travelling from the Earth to the Moon, back to Earth and half way back to the Moon again.

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This is a H-alpha picture sometimes a negative image can reveal hidden detail and this extremely long feature is now a filament and prominence as it traverses the western limb.

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Comparison of positive and negative images.

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To obtain the dimensions of these structures we can superimpose a “solar ruler� onto our images to scale the individual features.

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Negative image from 11 February and positive and negative from 9 February 2015.

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9 February this was my first attempt to measure it.

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Filaments can last for a few weeks or months and occupy magnetic inversion lines. The gas in a filament will eventually move to a different layer in the Sun and will no longer be visible in an image of the chromosphere. But at the same time, other gas may move into the chromosphere and create a new filament someplace else. The birth and death of filaments is a mystery and the subject of ongoing study by solar scientists. Sometimes we may be lucky enough to image these huge structures lifting off when they become unstable and I have caught numerous extreme examples of this phenomenon that are posted on my website. Two notable examples are 1 Prominence lift off: 2 Filament lift off: BY ANDREW DEVEY

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PT 2 Astrophotography Without a Tele


mounts Using an ordinary tripod, how long can you expose before star trailing becomes a problem? Trailing is influenced by four factors: Time The longer you expose, the more trailing you will get. Aperture The more light you can get onto your sensor, the shorter your

There are several ways to deal with this:

Motorized mount Inexpensive motoriz

getting more precise movement and align

ing it is done by pointing the axis of rotati

also work, but they aren’t needed at thes as a “barn-door mount.”

exposure can be. Magnification With a 35-mm lens and a camera with a DX or APS-C sensor, star trailing becomes objectionable after about 20 seconds. With a 200-mm lens on the same camera, stars begin to change into streaks after only 5 seconds. Declination The amount of trailing per unit time depends on the cosine of the angle from the celestial equator. In plain language, that means

Motorized telescope mounts gradually doing this and buy an autoguider, which

correction signals back to the mount. If y Manual tracking If your tripod permits

Probably the least fun option, but it’s how

if you point directly at the north or south pole, there will be no trail-

Stacking Take many short exposures a

ing, and you will get the most trailing for objects on the equator. For

because you might have to stack hundred

example, with a 200mm lens you can expose stars in Ursa Major for up

expose long enough that your signal is sa

to 5 seconds, but the longest you can expose the Orion Nebula without trailing is about 2 seconds.

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Increase the ISO This option increases Nikon D4, it may still be a good option.


escope- Thomas J. Nelson


zed mounts made specifically for this purpose are available. As your magnification approaches that of a telescope,

ning the mount with the Earth’s axis become more and more important. If you’re in the northern hemisphere, align-

tion of the mount toward Polaris. The more expensive German equatorial mounts used by amateur astronomers will

se levels of magnification, unless you want very long time exposures. Some people use a homemade device known

y become more inaccurate over time, and eventually need to be rebuilt or replaced. Most people get fed up with is a separate camera or section of a chip that locks on to a star and corrects the tracking of the mount by sending

you buy a telescope mount, make sure it can accept an autoguider input. it, you can also rotate the camera manually, using a separate monocular with a reticle to keep the object centered.

w they did it in the old days.

and stack them using a free software package like Deep Sky Stacker. This works well, but it’s a little inconvenient,

ds of frames. Stacking increases the signal and reduces the noise, and can produce excellent images. The trick is to

afely above the noise level of the camera, but not so long that the stars turn into streaks. the noise in your image, generally producing unsatisfactory results. However, if you have a high-end camera like a

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Use a faster lens Good option but expensive.

Nebulae (Added Sep 24, 2

Fix it in the computer Small amounts of trailing can be removed by deconvoluting the image. This is the worst option of all, because it not only increases the noise, it can create bad artifacts in the image. Only take pictures of Polaris This works well, but gets boring after awhile. Make the image really small If you shrink the image enough, they won’t notice the fact that your stars are actually short dashes. Give up Star trails are cool, too. As mentioned above, trailing can also be caused by zoom lenses zooming by themselves.

I mentioned above that nebulas are ideal subjects for astroph

with a regular camera because they are so big. But what exactly d to take good pictures of a nebula? Here’s a shopping list:

A motorized mount is essential, because you will be exposing fo to an hour.

At least one two-inch diameter narrow-band filter. Hydrogen

filters and Oxygen-III (OIII) filters are good to start. (Watch out: s

marked as Hα are really long-pass filters and will give terrible re

A 52-48 mm step-down ring, plus a set of step-down rings if y something other than 52 mm in diameter.

A fast, sharp lens. If your lens isn’t sharp, the stars will be so b will tend to cover up the nebula. clear, dark sky.

A camera modified for infrared. Some people modify their own c

there are many vendors who will do it for a fee. It’s a simple m

and the modified camera can usually still be used for regular ph If you save the parts it’s not difficult to convert it back.

For DSLRs, the newest bunch of cameras are preferred because th

more sensitive. Since you’ll be using a narrow-band filter, Live Vie Astro Nerds March 2015




do you need

or 5 minutes

n-alpha (HÎą)

some filters


your lens is

big that they

camera, but



Image of a portion of the Milky Way in the constellation of Cygnus using filters. This image was made without a telescope, using a Nikon D90 modified for infrared, and a CGEM motorized mount. The red channel is a single 10-minute exposure with a Baader 7 nm H-alpha filter. The green and blue channels

hey’re much

are a single 10-minute exposure with a Celestron 8-nm OIII filter. Lens: Nikkor f/1.2 50 mm, set at f/2.0,

ew focusing

ISO 400, no guiding (Cropped and resized). Astro Nerds March 2015


won’t work with the older cameras. You can still focus by trial and error, but a more sensitive camera, like Nikon’s D7100 or the Canon equivalent, will make the task much easier. Some nebulas are bright enough that you can dispense with some of the above items. For example, I’ve taken reasonably good pictures with a Hα narrowband filter of objects that were only a few degrees away from the full moon (dispensing with item no. 5). For a blue oxygen III filter, though, you need dark. A modified camera is only needed for Hα and SII, which are in the near-infrared. If you don’t want to risk modifying your camera, you can still take great pictures of some nebulas with an unmodified camera, using an OIII filter, but they will appear blue. Unfortunately, not all nebulas emit blue radiation. Photographic lenses are ideal for wide-angle shots like the photo of the nebulae in Cygnus shown above. This image combines the nebulas around the star Sadr, which is the center of the “cross” in Cygnus. The butterfly-shaped IC 1318 nebula in the center and the tiny C-shaped Crescent Nebula (NGC 6888) above and to its right appear red. The large white nebula at the lower left is the North America Nebula (NGC 7000). Just above it is the Pelican Nebula. The white parentheses-shaped one at lower right is the Veil Nebula (IC 1340). No telescope was used, but the camera was attached to a CGEM German equatorial mount. Compare this image with the image at the top of the page, where the North America nebula is just a faint pink smudge superimposed on the Milky Way background. Without a filter, it is virtually impossible to photograph the Veil nebula with a camera lens. With a filter, you almost can’t miss it.

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The sharpness of the lens makes a h

lens is not necessary. I tried the sam

came out as big fuzzy blobs. So I swit

to exactly the same point, so it’s nec


huge difference in pictures like this, because the stars are point sources. Don’t listen to people who tell you a sharp

me nebula on the same night with a f/1.8 35-mm lens, focused to perfection, and instead of sharp points, the stars

tched to a manual f/1.2 50-mm lens. The trade-off with this particular lens is that near-infrared and blue don’t focus

cessary to re-focus when switching filters.

What do filters do? The purpose of filters is to reduce the amount of light coming from stars, making them smaller. Getting the stars small prevents them from blocking the nebulas, which have much lower surface brightness than stars. A filter also reduces the sky background, which is spread out over all wavelengths. Emission nebulas emit most of their light in narrow emission lines corresponding to ionization of various elements. Since nebulas are mostly hydrogen, this means that HÎą usually gives the brightest signal. Non-emission nebulas, like the Witch Head Nebula, are not helped by using filters.

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More advanced techniques 22

Some objects are so large that it’s virtually impossible to photograph them with a telescope. That’s where the power of tel

but they might not realize that it’s surrounded by an even larger nebula called Barnard’s Loop (Sh2-276), which is over 12 ti

than the angular size of the Moon. Barnard’s Loop covers nearly 15% of the distance from the celestial equator to the pole.

At this scale, the entire Orion Nebula, which is about twice the apparent size of the moon, is only a small white blob in the

Photographing Barnard’s Loop with a telescope would be like photographing the Empire State Building with a microscope. Y

takingly stitching images together. The image below took less than an hour to photograph, plus another ten or twenty minu

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Barnard’s Loop in Orion is 320 light years across and only 1300 light years away, so its angular size is 13.8 degrees. (Modified D90 and 50-mm f/1.2 lens.) Compare this image with the one below from a monochrome CCD camera

lescope-free astronomy comes in. Most people are probably familiar with the gigantic Orion Nebula (see photo above),

times bigger, both in actual size and apparent size, with an angular size of almost 840 minutes of arc. That’s 28 times bigger

. Yet despite its size, it is far too faint to be seen with the naked eye, or even through the eyepiece of a typical telescope.

center, and the Horsehead Nebula is a tiny dark blip near Alnitak (the leftmost of the three large stars in Orion’s belt).

You could do it, and you’d certainly get better resolution and finer detail, but it would take weeks of exposing and pains-

utes of computer processing time.

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Here’s the equipment that was used for this image. A DSLR partially modified for infrared, set at ISO 800. CGEM motorized mount (aligned with Polaris using a polar scope). 2-inch H-alpha, 7 nm filter and a 52-48 mm step-down ring. Nikkor 50 mm f/1.2 lens set at f/2.0. A copy of Deep Sky Stacker. Image processing software (Imal or equivalent) to adjust the contrast. To make this image, I took 11 exposures of 5 minutes each with the Hα filter and 8 color exposures of 15 seconds with no filter. At f/2, with moderate levels of light pollution, you can only expose for 10-15 seconds before the the sky background starts to saturate the image sensor. If your lens is slower, you will need proportionately longer exposures. Because Barnard’s loop is so faint, the H-alpha filter is essential for blocking out the starlight. Almost nothing is visible through an O III filter; hydrogen is by far the strongest signal, so you need a camera that can photograph the near-infrared wavelength of hydrogen. That means either a modified DSLR or a specialized CCD astronomy camera. In Deep Sky Stacker, make sure to load the color images first, or the software may get confused and make the image completely red. The rule of thumb is: one second without a filter is equivalent to one minute with a filter.

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Cooled astronomy cameras


Compare this image with the one below taken using a cooled astronomy camera (total exposure 40 min). CCD cameras are more sensitive and have higher resolution than a DSLR. Images are smoother because of the greater pixel depth, but the cameras are harder to use. Generally they’re controlled by a laptop computer through a USB, ethernet, or serial cable. You can get comparable images with a DSLR, but it takes a lot longer. See linuxsetup137.html for details on setting up a CCD camera. What an astronomy camera buys you is more efficient use of your limited observing time. Barnard’s Loop photographed with the same Nikkor f/1.2 lens, but using a cooled astronomy camera instead of a DSLR. Left: Red=Hα, green=luminance and blue=blue. Right=Halpha only. These images were taken on a night when lots of airplanes were flying around, so they are crisscrossed with airplane trails. Nebulae are often shown in grayscale to make it easier to see the detail. Technically this was a cooled CCD camera, but in this instance additional cooling was not actually necessary. It was so cold that when I set the camera to −15C, instead of cooling down, the heater came on.

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Top Image: Barnard’s Loop Cropped, unresized image of Crescent Nebula (NGC 6888) taken with a Nikkor 50mm f/1.2 lens without a telescope using a cooled CCD camera and filters. Red=Hι, Green and Blue = OIII. Notice how the nebula is partially obscured by the stars. A telescope image would show more detail and the stars would be smaller, while a DSLR image would be fuzzier and many of the fainter stars would be lost in the noise. (Contrast-stretched and cropped to 1.46% of original area. CGEM motorized mount; total exposure 90 min.)

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Bottom Image: Veil nebula photographed with a 180 mm f/2.8 telephoto camera lens. Because the Veil Nebula is so big, most telescopes can only capture part of it at a time, but it’s a perfect match for this lens. I used a cooled monochrome CCD camera for this image. That allows you to re-focus after changing filters, which is necessary with most camera lenses. The limiting factor here was the blue-green background from the Moon, which was out while the picture was taken. I subtracted that from the image. Even so, it only took 20 minutes with each filter to get this image. (Red = H-alpha filter; Green and blue = OIII filter. Not cropped, but contrast-stretched and resized.

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LOOK UP- A GUIDE TO THE NIGTHT SKY March, 2015 SKYNOTES The Sun begins the month in the constellation of Aquarius but crosses the border into Pisces on the 12th at around 21h. It is climbing steeply now and daylight increases rapidly. On March 20th 22h45, the Vernal Equinox occurs, when the sun is directly overhead at the earth’s equator. The sun-earth distance at the time is 148,989,865 km. The astronomical season of spring begins and lasts for 92.74 days. If the earth had no atmosphere, day and night at this time would be exactly equal all over the planet except at the poles, but due to atmospheric refraction, this scenario occurs some days earlier. March is the best month to observe the mysterious Zodiacal Light during evenings when the moon is not present in the sky and you are well away from light pollution. Look towards the west when twilight has faded and you should see a faint cone of light pointing southwards at a steep angle of 60°. This year, the best dates to observe the zodiacal light are from the 7th to the 20th. The sun illuminating the disc of fine dust, which is the remnant of solar system formation 4.5 thousand million years ago, causes this phenomenon.

THE MOON The Moon is at perigee, its nearest to the earth, at 19h39 on the 19th, and at apogee, its furthest from the earth, at 07h00 the 5th.

Full Moon is on the 5th around 18h06 amongst the faint stars of southern Leo. Last Quarter Moon, is on March 13th at around 17h49 on the Ophiuchus/Sagittarius border and is the lowest Last Quarter moon of the year.

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New Moon is on the 20th at 09h37, just north of the intersection of the constellations Cetus, Pisces and Aries, during which the sun and moon are situated in this latter constellation. ECLIPSE! (see below)

First Quarter

takes place at

07h43 on March 27th in Gemini, in the vicinity of the star Alhena (gamma Geminorum) and is one of the highest First Quarter moons of the year.

Earthshine, (the faint glow on the night hemisphere of the moon caused by reflected sunlight from the earth), may be seen during the evenings on the dark hemisphere of the waxing crescent from the 21st to the 26th, and waning crescent from the 14th to the 19th.

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DEEP PARTIAL ECLIPSE OF THE SUN This is one of the best deep partial eclipses visible from the UK since August 1999, which you will remember was total in the SW corner of the UK. The shadow of the moon travels mostly north-west-wards along the north Atlantic, the Norwegian Sea and on towards the North Pole via the Arctic Ocean. There are two landfalls only and these are the Faroe Islands and the sparsely inhabited Norwegian Svalbard Islands. Interestingly the shadow of the moon leaves the earth in the vicinity of the North Pole as the sun is touching the horizon, having just risen after the long Arctic night. The reason for this is that although the Equinox does not take place until 13 hours later, when theoretically the sun’s disc should be only half visible, refraction in the earth’s atmosphere causes the entire disc to be seen. Unfortunately at this time of the year, cloud cover tends to be at its worst over the areas of totality. From Scarborough the eclipse begins at 08h29, when a small notch on the upper limb of the sun marks the appearance of the New Moon as it begins its crossing of the sun’s disc. The maximum phase is at 09h35, at which time the sun’s altitude in the SE is 28°. At this time, over 90% of the sun’s diameter will be hidden by the moon, and so observing the sun using the proper techniques of projection and special astronomical filters will allow you to see the sun at that moment as a thin crescent ‘lying on its back’. The appearance from Scarborough is as good, if not better than, the August 11th eclipse of 1999. The moon continues its eastward journey across the sun and leaves the solar disc at 10h44.

Here in Scarborough, I shall be at the Holbeck Clock Tower at the south end of The Esplanade (which affords easy access) at 8.15 am, with a couple of specialised telescopes to enable people to observe the eclipse safely. There will also be available a number of different types of solar filters for people to use. We hope the weather is fine, on this last day of winter! All are welcome. (see Safety Notes which follow these Skynotes!

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The Planets Mercury is not easily visible during March as it moves towards its superior conjunction beyond the sun in April. However, if you scan the ESE horizon at around 06h30 on the first few days of the month, you may spot the elusive planet within 5° of the horizon, which must be clear of all haze and obstructions Venus, in the faint constellation of Aries, is a splendid evening object and will be glimpsed from sunset onwards for three or more hours before the planet sets. There is no mistaking Venus, the ‘Evening Star’, (known to the ancients as Hesperus) as it shines as the brightest object in the sky after the sun and the moon. A couple of days after the solar eclipse, the moon will be seen as a thin crescent with ‘earthshine’ in the vicinity of Venus. On the 22nd from 19h onwards, the crescent moon lies 4° below and slightly to the left of Venus in the dusk sky. At the beginning of March, Mars sets a couple of hours after the sun, but the length of time the planet continues to be visible in the evening sky diminishes, until by the end of the month it sets some 20 minutes after 20h. The planet continues to move slowly eastwards in the constellation of Pisces. On the 1st of the month, Venus may help you to locate Mars as the two are comparatively close together in the fading twilight around 19h; Mars is the much fainter, reddish tinged object, lying just over 3° to the lower right of Venus. The ‘red planet’ is now far away from the earth and in order to see details on its surface you will require high magnification and a non-turbulent atmosphere, as it is only 10° above the western horizon in the fading twilight. The very Astro Nerds March 2015


thin crescent moon, with earthshine, is close to Mars during the evening of the 21st, when the planet is some 3° above the moon at that time and due west. Jupiter continues to shine brightly and steadily high in the vault of heaven amongst the faint stars of Cancer the Crab, just to the west of the constellation’s border with Leo. However, at the end of March the giant planet is setting at 04h. During the month the planet culminates (reaches its highest point in the south) just before midnight in the late evening. Remember to look for the four Galilean Satellites through firmly fixed binoculars as they change position from night to night. During the evening of the 2nd and 3rd of March, the broad gibbous, waxing moon

passes some 6° below Jupiter. As March begins, Saturn rises at 01h30, but before midnight at the month’s end. The ‘ringed planet’ lies in the constellation of Scorpius, just over one degree from the star Graffias (beta Scorpii). The northern surface of the ‘rings’, as seem from Earth, continues to be displayed well. The planet reaches a stationary point in its eastward motion on the 14th, where after, it begins to move retrograde towards the Libra border, as earth begins to overtake the planet ‘on the inside lane’. On the morning of the 12th, the gibbous waning moon may be seen approaching Saturn, which is the bright star-like object 2° (four moon widths) to the lower left of the moon. Saturn is admirably placed in its orbit for a good opportunity to see the northern ‘surface’ of the planet’s glorious ring system, even through a small telescope. In such an instrument, which inverts the image, you may be able to spot Titan, the largest Astro Nerds March 2015


of the Saturnian moons as a faint ‘star’ to the right of the planet on the 4th to the 6th and again from the 20th to the 22nd, and to the left of the planet from the 12th to the 14th and from the 28th to the 30th.

As the sky darkens on March 4th, around 19h30, use Venus to spot the remote planet Uranus, which early next month will be far beyond the sun at conjunction. on the 4th, the two objects are 10° above the western horizon, and if you turn your binoculars towards Venus, you will see Uranus as a faint object just 5 minutes of arc to the lower left of Venus (one sixth of a moon width). Both planets will be seen in the same field of view in binoculars and also in telescopes at low power(to the upper right) Neptune was in conjunction with the sun towards the end of last month and is too near the glare of our nearest star to be seen. Constellations visible in the south around midnight, mid-month, are as follows: Leo, the western part of Virgo, Crater, and Hydra. The Plough (Big Dipper), which is part of the constellation of Ursa Major, the Great Bear, is at the zenith, directly overhead. Clocks go forward an hour in the morning of Sunday March 29th (and ends on Sunday 25th October) All times are GMT

1° is one finger width at arm’s length.

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IMAGE CREDIT Jaspal Chadha Open Star Clusters M35 and NGC 2158

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Reader Profile: Jaspal Chadha Telescope: Altair Astro RC 250TT Mount: Ioptron CEM60 Other equipment (e.g. camera, binoculars, etc.): Sky watcher Esprit 100ED telescope and QSI 690CCD imaging camera

I have been into astronomy for just over three years now. I spent years looking various telescopes and eyepieces and enjoyed learning the night skies. I loved what I saw and wanted to share with others who were less fortunate to own a telescope and decided the best way to do that would be via images that I would capture. After months of research and trial and errors I finally invested in a setup that I think would work for me. My biggest challenges were to fend of the myths around imaging in city light polluted areas. I spent living my life in London and never thought I could get a better sky than this. I was totally wrong! Several hours out of London I was lucky enough to come across the most clearest and darkest skies. The challenge for

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me was to produce decent enough images to share, however knowing the light pollution would restrict me. I brought myself a CLS LP filter and attached it to the front of my imaging train, that helped reduced light pollution in the images that I took in colour, most commonly captured in RGB form.

I invested in a set of Narrow band filters and since then I have never looked back. Theses filters would cut straight though the light pollution and give me some

Cigar galaxy

decent images. Although capturing an image is some

M82 lies at an estimated distance of 12 million light years

what difficult, processing them is most time consuming as there are other techniques to really bring out the images.

Imaged from London on Xmas day, the conditions were extremely poor

For me Astrophotography has been very rewarding. You don’t need any expensive setup to produce NASA quality images nor live in the darkies parts of the world

Altair Astro RC 250TT

( Although it would help) My advice is to take small

ioptron CEM60 mount

steps, learn from your mistakes and keep working


towards your goal in Astrophotography.

L: 3 x 5 min RGB 3 x 10 min

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Three top tips I can recommend

1. Plan your imaging object in advance, use software like Stellarium to plan where your target is going to be in the sky and how much time you get capturing it. 2. Best time too image deep space objects like galaxies and nebulae is when the moon is not out in the night sky, this will ensure you have a nice dark sky. 3. Image when your desired object is just past the meridian line in the sky, that will ensure you have the best sky conditions and will help shy away from light pollution.


www.jkobse Astro Nerds March 2015


Cosmic clouds form fantastic shapes in the central regions of emission nebula IC 1805. The clouds are sculpted by stellar winds and radiation from massive hot stars in the nebula’s newborn star cluster, Melotte 15

Melotte 15 - The core of the Heart Nebula - London

RC 250TT Ioptron CEM60 QSI 690 CCD Ha 15 x 20min SII 8 x 20min OIII 8 x 20min Astro Nerds March 2015


Astro Nerds March 2015