GCN Circular 39988
Subject
GRB 250331E: Fermi GBM Final Real-time Localization
Date
2025-03-31T22:57:04Z (a month 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 22:46:32 UT on 31 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250331E (trigger 765153997.78765 / 250331949).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 196.6, Dec = -27.7 (J2000 degrees, equivalent to J2000 13h 06m, -27d 41'), with a statistical uncertainty of 14.0 degrees.
The angle from the Fermi LAT boresight is 73.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/quicklook/glg_skymap_all_bn250331949.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/bn250331949/quicklook/glg_healpix_all_bn250331949.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250331949/quicklook/glg_lc_medres34_bn250331949.gif