GCN 44134: SMA Detection of GRB 260310A / AT 2026fgk

2026-03-27T23:09:57.089Z | rev 0 | event: GRB 260310A

Anna Ho (Cornell), Garrett Keating (CfA), Kate Alexander (University of Arizona), Tanmoy Laskar (University of Utah), Raffaella Margutti (UC Berkeley) report on behalf of the POETS team:

On UT 2026 March 26 the Submillimeter Array (SMA) observed the position of GRB 260310A / AT2026fgk (GCN 43951, 43958, 43974), a nearby (z=0.153; GCN 43977) gamma-ray burst with bright radio emission at cm (GCN 44005, 44045) and mm (GCN 44057) wavelengths. Observations were obtained as part of the SMA Large Program, POETS (Pursuit of Extragalactic Transients with the SMA; PI Berger). Using the COMPASS pipeline we measure a preliminary flux density of 5.67 +/- 0.23 mJy at 230 GHz.

Further observations are planned. We thank the SMA staff for rapidly approving and scheduling these observations.