TITLE:   GCN CIRCULAR
NUMBER:  40758
SUBJECT: GRB 250617A: Fermi GBM Final Real-time Localization
DATE:    25/06/17 16:19:51 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 16:09:13 UT on 17 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250617A (trigger 771869358.345712 / 250617673).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 354.8, Dec = 35.4 (J2000 degrees, equivalent to J2000 23h 39m, 35d 23'), with a statistical uncertainty of 2.6 degrees.

The angle from the Fermi LAT boresight is 51.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250617673/quicklook/glg_skymap_all_bn250617673.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/bn250617673/quicklook/glg_healpix_all_bn250617673.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250617673/quicklook/glg_lc_medres34_bn250617673.gif