TITLE: GCN CIRCULAR NUMBER: 30727 SUBJECT: GRB 210827B: BALROG localization (Fermi Trigger 651751821 / GRB 210827424) DATE: 21/08/27 10:28:30 GMT FROM: Jochen Greiner at MPE,Garching jcg@mpe.mpg.de

J. Burgess, F. Kunzweiler, B. Biltzinger, F. Berlato, & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 651751821 at 10:10:16 on 27 Aug. 2021 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 305.1+/-2.9 deg Decl.(2000.0) = -17.3+/-2.3 deg We estimate an additional systematic error of 1 deg.

Further details are available at: https://grb.mpe.mpg.de/grb/GRB210827424/

The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB210827424/healpix

The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB210827424/json