TITLE:   GCN CIRCULAR
NUMBER:  40567
SUBJECT: GRB 250529A: Fermi GBM Final Real-time Localization
DATE:    25/05/29 03:56:55 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 03:46:16 UT on 29 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250529A (trigger 770183181.316048 / 250529157).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 7.1, Dec = 54.7 (J2000 degrees, equivalent to J2000 00h 28m, 54d 42'), with a statistical uncertainty of 4.2 degrees.

The angle from the Fermi LAT boresight is 60.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250529157/quicklook/glg_skymap_all_bn250529157.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/bn250529157/quicklook/glg_healpix_all_bn250529157.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250529157/quicklook/glg_lc_medres34_bn250529157.gif