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14th of July 2023
The mid-band Rapid ASKAP Continuum Survey
by Duchesne et al.
Duchesne et al. have recently published the Rapid ASKAP Continuum Survey (RACS) at 1367.5 MHz, "RACS-mid", which covers the whole sky south of a declination of +49 degrees. The images above 2MASS J10340385+1840490, a radio galaxy with both compact features and 1~2 arcminute diffuse components, as seen in the RACS-mid (right), NVSS (centre), and FIRST (right) surveys. (Note the colour scale varies between the three images due to the difference in angular resolution.)

The NVSS (NRAO VLA Sky Survey) observation was carried out in the VLA's D-configuration, with a minimum baseline of 35m and a maximum baseline of 1 km, whereas FIRST (Faint Images of the Radio Sky at Twenty centimetres) was conducted in the VLA's B-configuration, with a minimum baseline of 210m and a maxiumum baseline of 11 km. In contrast, ASKAP has a minimum physical baseline of 22m and a longest baseline of 6.4 km. Shorter baselines are more sensitive to extended source structure, which is why ASKAP and NVSS detect the radio lobes but FIRST does not. ASKAP's longer baselines than NVSS result in a higher angular resolution, which is why it can image the lobes in finer detail.

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