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.
apertifsurveys.wordpress.com). 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.
(email@example.com) 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 "shakedownâ€? 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.