TITLE: GCN CIRCULAR NUMBER: 40466 SUBJECT: GRB 250516A: Fermi GBM Final Real-time Localization DATE: 25/05/16 14:46:00 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 14:35:29 UT on 16 May 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250516A (trigger 769098934.27533 / 250516608).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 333.2, Dec = 0.1 (J2000 degrees, equivalent to J2000 22h 12m, 0d 06'), with a statistical uncertainty of 8.5 degrees.

The angle from the Fermi LAT boresight is 27.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250516608/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/bn250516608/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250516608/q...

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