ASKAP radio detections of possible candidate BD-21 1074 for GRB 240514E
ATel #16628; K. Rose (U. Sydney, CSIRO), T. Murphy (U. Sydney), L. Driessen (U. Sydney), E. Lenc (CSIRO), D. Kaplan (UWM), A. Anumarlapudi (UWM) on behalf of the VAST collaboration
on 21 May 2024; 06:38 UT
Credential Certification: Laura Driessen (laura@driessen.net.au)
Following the proposal of the triple-star system BD-21 1074 as a possible candidate for GRB 240514E (ATel #16622, GCN #36485, GCN #36501) we report the detection of highly circularly polarised radio emission from BD-21 1074 with the Australian SKA Pathfinder (ASKAP) as part of the third low-band epoch of the Rapid ASKAP Continuum Survey (RACS; McConnell et al. 2021).
We performed forced fitting on the publicly available ASKAP observations and measured Stokes I (S_I) and Stokes V (S_V) flux densities of:
| Date [UTC] |
S_I [mJy/beam] |
SNR_I |
S_V [mJy/beam] |
SNR_V |
Freq [MHz] |
| 2020 Mar 27.34 |
0.72 +/- 0.37 |
2.1 |
N/A |
N/A |
888 |
| 2021 Jan 23.56 |
0.86 +/- 0.21 |
4.7 |
-0.18 +/- 0.17 |
1.6 |
1367 |
| 2021 Jan 23.58 |
1.28 +/- 0.70 |
2.1 |
-0.95 +/- 0.59 |
1.6 |
1367 |
| 2021 Dec 17.75 |
0.70 +/- 0.27 |
3.0 |
N/A |
N/A |
855 |
| 2022 Jan 10.61 |
0.37 +/- 0.21 |
1.9 |
-0.29 +/- 0.19 |
1.6 |
1656 |
| 2024 Jan 01.64 |
1.84 +/- 0.50 |
4.0 |
-0.50 +/- 0.38 |
1.5 |
944 |
| 2024 Jan 01.65 |
2.01 +/- 0.39 |
6.1 |
-1.80 +/- 0.36 |
7.1 |
944 |
| 2024 Jan 05.62 |
1.55 +/- 0.27 |
6.8 |
-1.16 +/- 0.22 |
7.0 |
944 |
We consider the measurements with a signal-to-noise ratio (SNR) greater than 5 sigma to be significant detections.
The J2000 positions for the two RACS low-band observations (2024 Jan 01.65 and 2024 Jan 05.62) with SNR_I > 5 are:
(R.A., Dec) = (76.7065 deg, -21.5849 deg) = (05:06:49.56, -21:35:05.89)
(R.A., Dec) = (76.7061 deg, -21.5847 deg) = (05:06:49.47, -21:35:05.16)
with uncertainties of +/-2 arcsec in both R.A. and Dec.
All observations were conducted with a bandwidth of 288 MHz and a typical integration time of 15 minutes, with the exception of the 2 hour observation on 2021 Dec 17.75. The quoted uncertainties include the systematic flux scale uncertainty of approximately 6% and the RMS in quadrature with the fitted error. We note that these observations were conducted >4 months prior to the high-energy detections discussed in ATel #
16622.
This scientific work uses data obtained from Inyarrimanha Ilgari Bundara/the CSIRO's Murchison Radio-astronomy Observatory. We acknowledge the Wajarri Yamaji People as the Traditional Owners and native title holders of the Observatory site. CSIRO's ASKAP radio telescope is part of the Australia Telescope National Facility. Operation of ASKAP is funded by the Australian Government with support from the National Collaborative Research Infrastructure Strategy. ASKAP uses the resources of the Pawsey Supercomputing Research Centre. Establishment of ASKAP, the Observatory and the Pawsey Supercomputing Research Centre are initiatives of the Australian Government, with support from the Government of Western Australia and the Science and Industry Endowment Fund. This paper includes archived data obtained through the CSIRO ASKAP Science Data Archive, CASDA.
