The animation above shows the regions of the sky observed with ASKAP
(Australian
Square Kilometre Array Pathfinder) during the RACS-high
observations (Rapid ASKAP
Continuum Survey, high frequency band). The entire survey,
consisting of 1493 fields, was completed in just over 7 weeks
(including various maintenance periods and other ongoing Pilot Phase
II observations). During this period RACS observations used
approximately 16 days of total telescope time. The dynamic scheduling
software (SAURON - Scheduling Autonomously Under Reactive
Observational Needs) keeps an ever watchful eye on the telescope and
schedules RACS fields when they are highest in the sky whilst avoiding
the Sun and Moon (these can affect observations when nearby and so are
best avoided) and taking into account other environmental or system
constraints. This mode of observing means that fields are generally
tracked from right to left in the animation. Apart from observing the
RACS fields, every day or two SAURON will observe a calibrator source
to the south to ensure the data obtained from the telescope is
reliable - this gives the appearance of a heart beat in the animation
(the small yellow and purple disks show the position of the Sun and
Moon, respectively). The completion of RACS-high marks the third time
that ASKAP has observed the entire sky visible from the southern
hemisphere (the first two were for RACS-low and RACS-mid). Each is
observed in a different ASKAP frequency band and once processing of
the observations is complete it will be the radio equivalent of
observing in three colours - the different colours seen by the
telescope will aid in highlighting different physical processes at
play in the objects detected by RACS.
|