TITLE: GCN CIRCULAR NUMBER: 30784 SUBJECT: GRB 210905A: ATCA detection DATE: 21/09/08 23:15:54 GMT FROM: Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com> T. Laskar (University of Bath), S. Bhandari (CSIRO), R. Margutti (UC Berkeley), K. D. Alexander (Northwestern), E. Berger (Harvard), R. Chornock (UC Berkeley), D. Coppejans (Northwestern), M. Drout (U. Toronto), H. van Eerten (University of Bath), W. Fong (Northwestern), C. Guidorzi (U. Ferrara), C. G. Mundell (University of Bath), P. Schady (University of Bath), and G. Schroeder (Northwestern) report: "We observed GRB 210905A (Sonbas et al., GCN 30765) with the Australia Telescope Compact Array (ATCA) at multiple frequencies beginning on 2021 Sep 08 14:20 UT. We detect a radio counterpart at 5.5 and 9.0 GHz at a position consistent with the X-ray position (Beardmore et al., GCN 30768), optical position (Strausbaugh & Cucchiara, GCN 30769), and mm-band position (Laskar et al., GCN 30783) with a flux density of ~ 0.1 mJy at 9.0 GHz at a mid-time of 3.65 days after the burst. We thank the CSIRO staff for approving and scheduling 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. We acknowledge the Gomeroi people as the traditional owners of the Observatory site."