GCN Circular 39618
Subject
GRB 250307A: Fermi GBM Final Real-time Localization
Date
2025-03-07T20:08:14Z (6 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 19:57:53 UT on 7 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250307A (trigger 763070278.733804 / 250307832).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 265.6, Dec = 2.2 (J2000 degrees, equivalent to J2000 17h 42m, 2d 12'), with a statistical uncertainty of 2.7 degrees.
The angle from the Fermi LAT boresight is 82.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250307832/quicklook/glg_skymap_all_bn250307832.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250307832/quicklook/glg_healpix_all_bn250307832.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250307832/quicklook/glg_lc_medres34_bn250307832.gif