TITLE:   GCN CIRCULAR
NUMBER:  40025
SUBJECT: GRB 250403A: Fermi GBM Final Real-time Localization
DATE:    25/04/03 15:26:06 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 15:15:22 UT on 3 Apr 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250403A (trigger 765386127.830438 / 250403636).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 204.2, Dec = -25.4 (J2000 degrees, equivalent to J2000 13h 36m, -25d 23'), with a statistical uncertainty of 5.1 degrees.

The angle from the Fermi LAT boresight is 56.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250403636/quicklook/glg_skymap_all_bn250403636.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/bn250403636/quicklook/glg_healpix_all_bn250403636.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250403636/quicklook/glg_lc_medres34_bn250403636.gif