GCN Circular 40508
Subject
GRB 250521A: Fermi GBM Final Real-time Localization
Date
2025-05-21T04:37:01Z (4 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 04:27:02 UT on 21 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250521A (trigger 769494427.113864 / 250521185).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 213.0, Dec = 30.1 (J2000 degrees, equivalent to J2000 14h 11m, 30d 06'), with a statistical uncertainty of 4.6 degrees.
The angle from the Fermi LAT boresight is 74.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250521185/quicklook/glg_skymap_all_bn250521185.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/bn250521185/quicklook/glg_healpix_all_bn250521185.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250521185/quicklook/glg_lc_medres34_bn250521185.gif