GCN Circular 44636
Subject
GRB 260516B: Fermi GBM Final Real-time Localization
Event
Date
2026-05-16T05:23:15Z (14 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 05:12:36 UT on 16 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260516B (trigger 800601161.994496 / 260516217).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 161.5, Dec = 36.8 (J2000 degrees, equivalent to J2000 10h 46m, 36d 47'), with a statistical uncertainty of 4.8 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/2026/bn260516217/quicklook/glg_skymap_all_bn260516217.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260516217/quicklook/glg_healpix_all_bn260516217.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260516217/quicklook/glg_lc_medres34_bn260516217.gif