A second fast radio burst from the source of FRB 201124A detected by ASKAP

ATel #14508; Pravir Kumar (Swinburne University of Technology, SUT), R. M. Shannon (SUT), E. Keane (NUI Galway), V. A. Moss (CSIRO), on behalf of the ASKAP-CRAFT survey science project.
on 3 Apr 2021; 10:32 UT
Credential Certification: Ryan Shannon (rms72@cornell.edu)

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We report the detection of a second Fast Radio Burst (FRB) coincident with the FRB20201124A source, using the Australian Square Kilometre Array Pathfinder (ASKAP), as part of the Commensal Real-time ASKAP Fast Transient (CRAFT) survey science project. The burst, FRB 20210402A, was detected with a reported signal to noise ratio of 13.4 in the incoherent sum of 23 antennas. The system was operating with a central frequency of 1271.5 MHz, an observing bandwidth of 336 MHz, and a time resolution of 1.2 ms.

The properties of the burst are as follows:
Date: 2021-04-02.24235085
UTC: 05:48:59.114(1)
RA(J2000): 05:08(1)
DEC(J2000): 26:02(10)
Fluence: 22(3) Jy ms
Dispersion measure: 414 (3) pc cm^-3
Quoted uncertainties are with 90% confidence. The burst position and dispersion measure are consistent with the previously reported ASKAP burst (ATel #14502), and that reported by the CHIME/FRB collaboration (ATel #14497).

We note that both ASKAP-detected bursts were very bright, and with flux concentrated at the lower end of both bands. The reported fluences average over the entire band. We estimate that a 20-metre diameter antenna (with aperture efficiency of 0.63 and system temperature of 30 K) could have detected the first 700-800 MHz burst at a signal to noise ratio of 10. The second 1100-1200 MHz burst would have been detected at the same signal to noise ratio by a 40-metre antenna.

These bursts would have had S/N values of ~2800 and ~800 respectively if detected with the largest effective apertures currently available, meaning follow-up with high-gain instruments may reveal more weaker pulses. However, given the brightness of these bursts, follow-up with radio dishes of all sizes would likely be fruitful.

A plot of the dynamic spectrum of the burst can be found here: