GCN Circular 45494
Subject
GRB 260818A: ATCA detection of a candidate radio counterpart
Event
Date
2026-09-02T03:38:38Z (a day ago)
From
Tao An at USTC <antao@shao.ac.cn>
Via
Web form
Tao An (USTC), Ailing Wang (YNAO, CAS) report on behalf of a large collaboration:
We observed the field of GRB 260818A (Yin et al., GCN 45391; EP-FXT X-ray afterglow: GCN 45400, 45434) with the Australia Telescope Compact Array (ATCA), starting at 2026-08-30 10:48:49 UTC (12.4 days after the SVOM/ECLAIRs trigger). Data were obtained simultaneously at central frequencies of 6.53 GHz and 10.36 GHz.
The 1-sigma image rms noise levels are 9.5 uJy/beam at 6.53 GHz and 7.5 uJy/beam at 10.36 GHz.
A radio source is detected both frequencies at a significance >~ 7 sigma at R.A. (J2000) = 23:20:25.422, Dec. (J2000) = −32:05:49.60, consistent with the fading X-ray afterglow EPF_J232025.8-320549 (Plasse et al., GCN 45434). A detailed analysis is underway.
Further ATCA observations are being considered to test for radio variability and to confirm the association with the high-energy transient.
We thank the CSIRO Space and Astronomy staff, in particular Jamie Stevens, for supporting these observations. The Australia Telescope Compact Array is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO.