During the recent repeat observation of the
historic lunar
occultation of the radio source 3C273 with the Parkes radio
telescope, ASKAP also observed the "emersion" event. We couldn't
observe the immersion because the Moon/3C273 rose later in the Murchison
compared to at Parkes. The movie above is a combination of 720
ten-second snapshots taken with ASKAP over the course of the
event. The radio source 3C273 is about 1000 times brighter than the
Moon and many of the other weaker objects seen in this part of the
sky. This difference in brightness and the complex structure of the
moon poses many challenges in imaging the event. Nonetheless, ASKAP
provided a nice complementary view of the occultation, and showed
another fainter radio source that was also occulted around the same
time (MRC 1226+022). Note the unusual glow at the centre of the lunar
disc -- this is radio frequency interference from the Earth being reflected back
towards us!
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