GCN Circular 39391
Subject
GRB 250220B: Fermi GBM Final Real-time Localization
Date
2025-02-21T00:00:55Z (2 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 23:50:24 UT on 20 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250220B (trigger 761788229.197974 / 250220993).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 39.3, Dec = 45.6 (J2000 degrees, equivalent to J2000 02h 37m, 45d 36'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 3.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250220993/quicklook/glg_skymap_all_bn250220993.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/bn250220993/quicklook/glg_healpix_all_bn250220993.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250220993/quicklook/glg_lc_medres34_bn250220993.gif