| 5th of July 2021 |
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| ASKAP imaging of the LMC |
| by Pennock et al. |
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The ATCA imaged the LMC in the 1990s by mosaicking 1344 different
pointings of the array, in four different array configurations, taken
over 1.5 years. The power of ASKAP as a survey telescopes is
illustrated by the fact it was able to image the entire LMC in under
13 hours. The observations, covering 120 sq degrees, were made on
2019 April 20 using ASKAP’s full array of 36 antennas. ASKAP's
instantaneous field of view is ~30 square degrees, and so the LMC was
covered by four pointings (∼3h10m each), each with three interleaves (slight
offsets) to result in more uniform depth across the field -- effectively 12 pointings.
Pennock et al. have recently presented an analysis of a new ASKAP radio continuum image of the Large Magellanic Cloud (LMC) at 888 MHz with a beam size of 13.9 arcsec × 12.1 arcsec, They present a catalogue of 54,612 sources, divided over a Gold list (30,866 sources) complete down to 0.5 mJy, a Silver list (22,080 sources) of fainter sources, and a Bronze list (1,666 sources) of visually inspected sources in areas of high noise and/or near bright complex emission. While the source lists are dominated by extragalactic sources seen behind the LMC, the detections include planetary nebulae, young stellar objects, HII regions, supernova remnants, bubbles, novae and X-ray binaries in the LMC. The image above shows the region around 30 Doradus, a large HII region that is the most conspicuous object in the LMC. Also known as the Tarantula Nebula, 30 Doradus is named as it was the 30th nebula in the constellation of Doradus in a catalogue produced by Johann Bode in 1801. The name Tarantula Nebula arose in the 20th century from its appearance in deep photographic exposures. HII regions are ionized by ultraviolet light from young stars and 30 Doradus is thought to be the most active starburst region in the Local Group of galaxies. |