TITLE:   GCN CIRCULAR
NUMBER:  41575
SUBJECT: GRB 250828A: Fermi GBM Final Localization
DATE:    25/08/28 13:52:06 GMT
FROM:    A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it>

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

"At 12:00:02.52 UT on 28 August 2025, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 250828A (trigger 778075207/250828500).
This trigger was initially classified as Unreliable location by the flight software,
but is in fact a GRB.

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 220.44, Dec = -69.39 (J2000 degrees, equivalent to J2000 14h 41m, -69d 23m'),
with a statistical uncertainty of 3.08 degrees.

The angle from the Fermi LAT boresight is 14 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250828500/quicklook/glg_skymap_all_bn250828500.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/bn250828500/quicklook/glg_healpix_all_bn250828500.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250828500/quicklook/glg_lc_medres34_bn250828500.gif"