TITLE: GCN CIRCULAR NUMBER: 30783 SUBJECT: GRB 210905A: ALMA detection DATE: 21/09/07 23:00:31 GMT FROM: Tanmoy Laskar at U of Bath <tanmoylaskar@gmail.com> T. Laskar (University of Bath), K. D. Alexander (Northwestern), R. Margutti (Berkeley), E. Berger (Harvard), W. Fong (Northwestern), R. Chornock (Berkeley), C. G. Mundell (University of Bath), and P. Schady (University of Bath) report on behalf of a larger collaboration: "We observed GRB 210905A (Sonbas et al. GCN 30765) with the Atacama Large Millimeter/Submillimeter Array (ALMA) at 97.5 GHz beginning on 2021 September 05 23:41 UT (0.98 days after the burst). Preliminary analysis reveals a mm source with flux density of ~ 0.1 mJy at position: RA (J2000) = 20:36:11.5685 (+/- 0.0002) Dec (J2000) = -44:26:24.840 (+/- 0.002) consistent with the X-ray position (Beardmore et al., GCN 30768) and optical position (Strausbaugh & Cucchiara, GCN 30769). We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help with these observations."