TITLE: GCN CIRCULAR NUMBER: 30873 SUBJECT: Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB DATE: 21/09/23 22:03:59 GMT FROM: Joe Mangan at UCD <joseph.mangan@ucdconnect.ie> J.Mangan (UCD), S.Lesage (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: The Fermi Gamma-ray Burst Monitor (GBM) trigger 654090581/210923493 at 11:49:36.820 UT on 23 September 2021, tentatively classified as a GRB (GCN 30865), is in fact not due to a GRB. This trigger is likely due to a terrestrial electron beam (TEB).