TITLE: GCN CIRCULAR NUMBER: 40348 SUBJECT: GRB 250505A: Fermi GBM Final Real-time Localization DATE: 25/05/05 08:19:09 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 08:08:39 UT on 5 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250505A (trigger 768125324.539978 / 250505339).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 104.6, Dec = -10.3 (J2000 degrees, equivalent to J2000 06h 58m, -10d 18'), with a statistical uncertainty of 3.4 degrees.

The angle from the Fermi LAT boresight is 22.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250505339/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/bn250505339/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250505339/q...

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