TITLE: GCN CIRCULAR NUMBER: 22252 SUBJECT: GRB 171205A: ALMA observations DATE: 17/12/13 12:32:39 GMT FROM: Daniel Perley at Liverpool JMU D. A. Perley (LJMU), S. Schulze (Weizmann), and A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI) report on behalf of a larger collaboration: We observed the millimeter afterglow of GRB 171205A (D'Elia et al., GCN 22177; de Ugarte Postigo, GCN 22187) using the Atacama Large Millimeter/Submillimeter Array (ALMA). Observations were taken using the band 3 (92 GHz) and band 7 (340 GHz) receivers. The band 3 observations were carried out between 2017-12-11 09:40-10:01 UT (6.10 days after trigger) and the band 7 observations were carried out between 10:02-11:04 UT (6.13 days after trigger). In a preliminary reduction, the afterglow is strongly detected (S/N > 100) in both channels. We estimate a flux density of 28 mJy at 92 GHz and a flux of 16 mJy at 340 GHz, with calibration uncertainties of ~15% and ~25%, respectively. We expect these uncertainties to improve significantly after a full reduction. Further observations are planned. We acknowledge the support of the ALMA staff in conducting these observations rapidly, in particular Anita Richards, Andy Biggs, and Eelco van Kampen. ________________________________ Important Notice: the information in this email and any attachments is for the sole use of the intended recipient(s). If you are not an intended recipient, or a person responsible for delivering it to an intended recipient, you should delete it from your system immediately without disclosing its contents elsewhere and advise the sender by returning the email or by telephoning a number contained in the body of the email. No responsibility is accepted for loss or damage arising from viruses or changes made to this message after it was sent. The views contained in this email are those of the author and not necessarily those of Liverpool John Moores University.