TITLE:   GCN CIRCULAR
NUMBER:  41896
SUBJECT: GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
DATE:    25/09/20 05:33:44 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
780029651 at 02:54:06 on 20 Sept. 2025 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 is:
RA(2000.0) = 174.6 deg
Decl.(2000.0) = 52.8 deg
The 1 sigma statistical error radius is 1.9 deg.
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB250920121/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB250920121/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB250920121/json