TITLE: GCN CIRCULAR NUMBER: 41473 SUBJECT: GRB 250821B: Fermi GBM Final Localization of a Bright Burst DATE: 25/08/21 19:00:29 GMT FROM: Jacob Smith at Fermi-GBM Team jrs0118@uah.edu
The Fermi GBM team reports the detection of a likely LONG GRB
"At 16:07:47.46 UT on 21 August 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250821B (trigger 777485272/250821672).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 39.95, Dec = -77.13 (J2000 degrees, equivalent to J2000 2h 39m, -77d 7'), with a statistical uncertainty of 1.00 degrees.
The angle from the Fermi LAT boresight is 67 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250821672/q...
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250821672/q...
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250821672/q..."
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