TITLE:   GCN CIRCULAR
NUMBER:  39389
SUBJECT: GRB 250220A: Fermi GBM Final Real-time Localization
DATE:    25/02/20 22:19:28 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 22:09:01 UT on 20 Feb 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250220A (trigger 761782146.820828 / 250220923).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 194.6, Dec = -60.9 (J2000 degrees, equivalent to J2000 12h 58m, -60d 53'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 171.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250220923/quicklook/glg_skymap_all_bn250220923.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/bn250220923/quicklook/glg_healpix_all_bn250220923.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250220923/quicklook/glg_lc_medres34_bn250220923.gif