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2nd of July 2019
ASKAP localisation of a Fast Radio Burst
by Bannister et al.
In a paper published in Science, Bannister et al. describe observations with ASKAP to determine the precise location of a Fast Radio Burst (FRB). The galaxy from which the burst originated was then imaged by three of the world's largest optical telescopes - Keck, Gemini South and the European Southern Observatory's Very Large Telescope. Fast radio bursts last less than a millisecond, making it difficult to accurately determine where they have come from. Most FRBs are "one-offs" but a small fraction are "repeaters" that recur in the same location. In 2017 astronomers identified a repeating FRB's home galaxy but localising a one-off burst has been much more challenging. ASKAP was able to pinpoint the location of FRB 180924 to its home galaxy (DES J214425.25-405400.81), with the high-resolution image showing that the burst originated in the outskirts of a Milky Way-sized galaxy about 3.6 billion light-years away. The image above, obtained with ESO's 8-m Very Large Telescope, shows the host galaxy with the FRB location marked by the black circle. The redshift of the galaxy, indicating its distance, was measured with spectra obtained with 10-m Keck telescope in Hawai'i and the 8-m Gemini South telescope in Chile. While only a millisecond or so in duration at any frequency, FRBs are dispersed in time, with lower frequencies arriving later than higher frequencies. The amount of dispersion depends on the amount of matter the radio waves traverse in reaching the Earth. By pinpointing their position, FRBs can be used to measure the amount of matter in intergalactic space, potentially revealing material that astronomers have struggled for decades to find.

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