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Gearing up for Apertif operations

planning observations and related tasks. We

beams, amounting to nearly three thousand

also used ARTAMIS (All-Round Telescope Array

beams on sky. The main effort has been to

Monitoring and Information System) for real-

automatically process the resulting data and

time monitoring, and tested automation for

classify the many candidate transients detected

the Apertif imaging inspection plots (see: http://

by the ARTS pipeline in each of these beams. To drastically reduce the number of beams

Apertif is about to transition from development into operations. We have recently stress tested the system and verified if all elements needed for operations are in place.

The time-domain mode of Apertif is controlled

required to fill the entire Apertif field of view,

by a dedicated backend, the Apertif Radio

ARTS was run in an incoherent mode during

Transient System (ARTS). ARTS is built of forty

the shakedown period. This comes at the

servers equipped with four high-performance

cost of reduced sensitivity. The ARTS pipeline

GPU cards each. In itself, it is the most powerful

was running alongside the observations

computational system available in the

in real-time and e-mailing a summary of

Betsey Adams, Ă gnes Mika, Vanessa Moss,

Netherlands. Getting all these GPU-equipped

interesting candidates to the team. This led

Leon Oostrum and Arno Schoenmakers on

servers to behave properly has proven to be a

to the detection of single pulses from pulsar

behalf of the Apertif and ARTS teams

complicated yet rewarding process.

B1933+16, as shown in Figure 2.

( For each of the forty compound beams Early Apertif surveys will start on 1 January

produced by the Apertif beamformers, ARTS

2019. In order to prepare for this new phase,

can create multiple coherently added tied-array

we carried out an Apertif "shakedown� from 12 to 22 October. The aim was to test the operational readiness of the imaging, timedomain and calibration modes as well as the archiving capabilities. Thanks to the efforts of many people, the shakedown period was an overall success, while also identifying lots of areas to improve before the real start in January. The shakedown period provided a great opportunity to highlight some of the operational tools that have been developed at ASTRON (Figure 1). Two key aspects of the Apertif data flow are ALTA (Apertif Long-Term Archive) and ATDB (Apertif Task Database). ALTA is a 1.5 PB data repository which stores data and metadata for both the imaging and time-domain modes, while ATDB has recently been adopted for imaging, handling everything from observation specification and scheduling to ingest to ALTA. ATDB greatly increases the efficiency of preparing and


ASTRON News / Winter 2018

Figure 1: The Apertif shakedown made use of various operational tools, such as ATDB, ALTA, ARTAMIS and a fully-automated inspection plot procedure. Image credit: N. Vermaas, H. Mulder, V. Moss.

ASTRON News Winter 2018  
ASTRON News Winter 2018