TITLE:   GCN CIRCULAR
NUMBER:  40538
SUBJECT: GRB 250523A: Fermi GBM Final Real-time Localization
DATE:    25/05/23 14:36:55 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 14:26:23 UT on 23 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250523A (trigger 769703188.305002 / 250523602).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 52.9, Dec = 55.2 (J2000 degrees, equivalent to J2000 03h 31m, 55d 12'), with a statistical uncertainty of 3.0 degrees.

The angle from the Fermi LAT boresight is 38.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/quicklook/glg_skymap_all_bn250523602.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/bn250523602/quicklook/glg_healpix_all_bn250523602.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250523602/quicklook/glg_lc_medres34_bn250523602.gif