GCN Circular 43907
Subject
GRB 260303B: Fermi GBM Final Real-time Localization
Event
Date
2026-03-03T13:34:53Z (2 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 13:24:20 UT on 3 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260303B (trigger 794237065.456588 / 260303559).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 9.3, Dec = -26.7 (J2000 degrees, equivalent to J2000 00h 37m, -26d 41'), with a statistical uncertainty of 1.6 degrees.
The angle from the Fermi LAT boresight is 67.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260303559/quicklook/glg_skymap_all_bn260303559.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/bn260303559/quicklook/glg_healpix_all_bn260303559.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260303559/quicklook/glg_lc_medres34_bn260303559.gif