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5th of October 2023
ASKAP Variable Sources on Minute Timescales
by Wang et al.
Wang et al. present results from a radio survey for variable and transient sources on 15-min timescales, using ASKAP pilot survey data. The variability search was conducted within each 8–10 hour pilot survey observation on a 15-min timescale. In total, 38 variable and transient sources were detected: eight of which are stars, only one of which had previously identified as a radio star. Their light-curves have diverse morphologies and flare durations. After checking their dynamic spectra, it was found two stars have even shorter flares than 15 minutes. One is CD-28 302 showing a ∼5 min multi-component burst reaching a flux density of 45.6 mJy/beam, and the other is 2MASS J10491880−2509235 showing a 100% circularly polarised burst lasting about 1 minute and reaching a flux density of 35.5 mJy/beam.

The figures above show the total intensity dynamic spectra of these two flaring stars: CD-28 302 (left panel) and 2MASS J10491880−2509235 (right panel). The temporal and spectral resolution are 10 s and 1 MHz, respectively. This is the first large-scale radio survey for variables and transient sources on minute timescales at a sub-mJy sensitivity level. The team expect to discover ∼1 highly variable source per day using the same technique on the full ASKAP surveys.

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