TITLE: GCN CIRCULAR NUMBER: 39876 SUBJECT: GRB 250327A: Fermi GBM Final Real-time Localization DATE: 25/03/27 07:40:37 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 07:30:06 UT on 27 Mar 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250327A (trigger 764753411.32631 / 250327313).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 246.1, Dec = 62.3 (J2000 degrees, equivalent to J2000 16h 24m, 62d 17'), with a statistical uncertainty of 3.6 degrees.

The angle from the Fermi LAT boresight is 47.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/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/bn250327313/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250327313/q...

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