GCN Circular 41432
Subject
GRB 250820A: Fermi GBM Final Real-time Localization
Event
Date
2025-08-20T00:42:49Z (5 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 00:32:21 UT on 20 Aug 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250820A (trigger 777342746.588176 / 250820022).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 28.0, Dec = -70.8 (J2000 degrees, equivalent to J2000 01h 52m, -70d 47'), with a statistical uncertainty of 1.1 degrees.
The angle from the Fermi LAT boresight is 169.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250820022/quicklook/glg_skymap_all_bn250820022.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/bn250820022/quicklook/glg_healpix_all_bn250820022.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250820022/quicklook/glg_lc_medres34_bn250820022.gif