GCN Circular 45155
Subject
GRB 260705A: ATCA radio observations
Event
Date
2026-07-14T14:38:03Z (7 days ago)
From
James Leung at U. Toronto / HUJI <jamesk.leung@utoronto.ca>
Via
Web form
J. K. Leung (U. Toronto/HUJI), G. E. Anderson (CSIRO), S. Chastain (TTU), L. Rhodes (TSI/McGill), A. Gulati (U. Sydney), A. J. van der Horst (GWU) on behalf of the PanRadio GRB collaboration
We performed observations of GRB 260705A, which was detected by SVOM/ECLAIRs (Saccardi et al., GCN 45079) and Fermi/GBM (Hamburg, GCN 45080), using the Australia Telescope Compact Array (ATCA) from 14:30 - 23:00 UT on 11 July 2026 (~6.3 days post-burst) using the 4cm (4-12 GHz) receiver. Our observations were centred on the position of the candidate optical counterpart detected by SOAR and Gemini-South telescopes (Freeburn et al., GCN 45105).
In our preliminary analysis, we do not detect any radio source with a position consistent with the candidate optical counterpart. The rms noise of the observation at 8 GHz was 8 microJy/beam. However, we find multiple radio sources within the SVOM/ECLAIRs error circle (Saccardi et al., GCN 45079) that were not detected in the Rapid ASKAP Continuum Survey (RACS; McConnell et al., PASA, 37, e048) and will continue to monitor these sources.
In regards to the possible association with GRB 260705B (Freeburn et al., GCN 45105), we note that the separation between the reported positions for GRB 260705A (Saccardi et al., GCN 45079) and GRB 260705B (Fermi GBM Team, GCN 45081) is ~11 deg; with the uncertainties on the positions being 7.06 arcmin and 3.0 deg, respectively; the positions of these GRBs are not statistically consistent.
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.