TITLE:   GCN CIRCULAR
NUMBER:  39057
SUBJECT: GRB 250128B: Fermi GBM Final Real-time Localization
DATE:    25/01/28 16:33:27 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 SHORT GRB

At 16:22:53 UT on 28 Jan 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250128B (trigger 759774178.772694 / 250128683).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 264.8, Dec = -46.6 (J2000 degrees, equivalent to J2000 17h 39m, -46d 36'), with a statistical uncertainty of 8.2 degrees.

The angle from the Fermi LAT boresight is 145.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250128683/quicklook/glg_skymap_all_bn250128683.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/bn250128683/quicklook/glg_healpix_all_bn250128683.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250128683/quicklook/glg_lc_medres34_bn250128683.gif