TITLE:   GCN CIRCULAR
NUMBER:  40596
SUBJECT: GRB 250601A: Fermi GBM Final Real-time Localization
DATE:    25/06/01 17:40:08 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 17:29:35 UT on 1 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250601A (trigger 770491780.538054 / 250601729).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 86.5, Dec = -55.7 (J2000 degrees, equivalent to J2000 05h 46m, -55d 42'), with a statistical uncertainty of 4.5 degrees.

The angle from the Fermi LAT boresight is 23.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250601729/quicklook/glg_skymap_all_bn250601729.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/bn250601729/quicklook/glg_healpix_all_bn250601729.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250601729/quicklook/glg_lc_medres34_bn250601729.gif