| 11th of July 2023 |
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| The mid-band Rapid ASKAP Continuum Survey |
| by Duchesne et al. |
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ASKAP is surveying the sky in three frequency bands across its
operational frequency range.
The first pass of the Rapid ASKAP Continuum Survey (RACS) at 887.5 MHz, "RACS-low",
was completed in 2020.
Duchesne et al. now present the second observing pass
at 1367.5 MHz, "RACS-mid",
which covers the whole sky south of a declination of +49 degrees.
The image above shows the tiling of the celestial sphere for RACS-mid, with a view centered on a declination of −27 degrees (i.e., the zenith as viewed from ASKAP). With the smaller footprints at the higher frequency, the number of tiles required has increased to 1493 from the 903 required for RACS-low. Aside from this increase in pointings, the tiling is similar to RACS-low and features the same quasirectangular grid over the South Celestial Pole (SCP). As only a minimal increase in noise was seen in the higher-declination strips of RACS-low, the decision was made to observe further north for subsequent RACS passes. For RACS-mid, the survey pointings continue to a declination of +46 degrees, to test the performance at the elevation limits of the telescope, with the image edges reaching a declination of +49 degrees. RACS-low was observed up to a declination of +37 degrees, with image sensitivity up to +41 degrees, while the resulting catalogue was restricted to declinations below +30 degrees. |