TITLE: GCN CIRCULAR NUMBER: 34518 SUBJECT: GRB 230815A: ATCA detection of radio counterpart DATE: 23/08/22 11:44:32 GMT FROM: James Leung at U of Sydney/VAST J. K. Leung (USyd), G. E. Anderson (Curtin), S. D. Ryder (Macquarie), A. J. van der Horst (GWU), A. Gulati (USyd), L. Rhodes (Oxford), S. Chastain (UNM) on behalf of the PanRadio GRB collaboration The Australia Telescope Compact Array (ATCA) observed long GRB 230815A (Klingler et al., GCN 34434; Mailyan et al., GCN 34440) as part of the ATCA "PanRadio GRB" follow-up Large Project C3542 (PI. Anderson) on 2023-08-17 UT and 2023-08-18 UT. No radio sources were detected at the GRB location in the first observation conducted from 2023-08-17 02:00 UT for 10 hrs at 5.5, 9.0, 16.7 and 21.2 GHz. The 3-sigma upper limits were 75, 69, 324, 741 microJy/beam, respectively. Note the higher than usual rms was due to bad weather during the observation. The second observation was conducted from 2023-08-18 22:00 UT for 6 hrs at 5.5, 9.0 and 44 GHz. In our preliminary analysis, we detect a radio counterpart with a flux density of 70+/-10 microJy at 9 GHz. The fitted position is: RAJ2000 = 12:18:53.2 DECJ2000 = -58:03:09.0 with an uncertainty of ~0.3". This is in broad agreement with previously reported Swift/XRT (Beardmore et al., GCN 34437) and VLT/HAWK-I (Schneider et al., GCN 34467) afterglow positions. There was also a marginal ~3 sigma detection at 5.5 GHz (rms=14 microJy/beam) and a non-detection at 44 GHz with a 3-sigma upper limit of 111 microJy/beam. Further observations are planned. We thank the CSIRO Space and Astronomy staff for supporting these observations. We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.