TITLE: GCN CIRCULAR NUMBER: 42499 SUBJECT: GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143) DATE: 25/10/28 04:28:32 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 783314796 at 03:26:31 on 28 Oct. 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) = 145.7 deg Decl.(2000.0) = 16.8 deg The 1 sigma statistical error radius is 2.1 deg. We estimate an additional systematic error of 2 deg.

Further details are available at: https://grb.mpe.mpg.de/grb/GRB251028143/

The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251028143/healpix

The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251028143/json

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