TITLE:   GCN CIRCULAR
NUMBER:  40050
SUBJECT: GRB 250404A: Fermi GBM Final Real-time Localization
DATE:    25/04/04 14:30:25 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 14:19:46 UT on 4 Apr 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250404A (trigger 765469191.347644 / 250404597).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 123.4, Dec = 34.1 (J2000 degrees, equivalent to J2000 08h 13m, 34d 06'), with a statistical uncertainty of 1.2 degrees.

The angle from the Fermi LAT boresight is 42.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250404597/quicklook/glg_skymap_all_bn250404597.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/bn250404597/quicklook/glg_healpix_all_bn250404597.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250404597/quicklook/glg_lc_medres34_bn250404597.gif