TITLE:   GCN CIRCULAR
NUMBER:  39703
SUBJECT: GRB 250313A: Fermi GBM Final Real-time Localization
DATE:    25/03/13 14:44:53 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 14:34:33 UT on 13 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250313A (trigger 763569278.689058 / 250313607).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 276.4, Dec = 51.8 (J2000 degrees, equivalent to J2000 18h 25m, 51d 47'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 4.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250313607/quicklook/glg_skymap_all_bn250313607.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/bn250313607/quicklook/glg_healpix_all_bn250313607.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250313607/quicklook/glg_lc_medres34_bn250313607.gif