GRB 261101B
GCN Circular 46127
Subject
GRB 261101B: BALROG localization (Fermi Trigger 815240277 / GRB 261101651)
Date
2026-11-01T16:00:44Z (3 days ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
815240277 at 15:37:52 on 01 Nov. 2026 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) = 316.3 deg
Decl.(2000.0) = 9.8 deg
The 1 sigma statistical error radius is 3.3 deg.
We estimate an additional systematic error of 2 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB261101651/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB261101651/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB261101651/json
GCN Circular 46126
Subject
GRB 261101B: Fermi GBM Final Real-time Localization
Date
2026-11-01T15:48:21Z (3 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 15:37:52 UT on 1 Nov 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261101B (trigger 815240277.50196 / 261101651).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 321.6, Dec = 14.6 (J2000 degrees, equivalent to J2000 21h 26m, 14d 35'), with a statistical uncertainty of 2.0 degrees.
The angle from the Fermi LAT boresight is 89.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261101651/quicklook/glg_skymap_all_bn261101651.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261101651/quicklook/glg_healpix_all_bn261101651.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261101651/quicklook/glg_lc_medres34_bn261101651.gif