TITLE: GCN CIRCULAR NUMBER: 31808 SUBJECT: GRB 220331A: Fermi GBM Final Real-time Localization DATE: 22/03/31 18:47:19 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 18:37:02 UT on 31 Mar 2022, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 220331A (trigger 670444627.268388 / 220331776).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 12.8, Dec = 2.9 (J2000 degrees, equivalent to J2000 00h 51m, 2d 53'), with a statistical uncertainty of 4.1 degrees.

The angle from the Fermi LAT boresight is 58.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220331776/q...

The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220331776/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2022/bn220331776/q...