GCN Circular 35221

V. Sharma (NASA-GSFC/UMBC) and O. Roberts (NASA-MSFC/USRA) report on behalf of the Fermi GBM Team:

"At 19:10:18.11 UT on 29 November 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231129C (trigger 722977823/231129799).

The GBM light curve consists of a very bright pulse, with a duration of about 15 seconds. This event, a likely, long GRB, is very bright and follow-up across all wavelengths is encouraged.

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 2.04, Dec = -81.53 (J2000 degrees, equivalent to J2000 00h 08m, -81d 32'), with a statistical uncertainty of 1.00 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).

The angle from the Fermi LAT boresight is 50 degrees.

A full science circular is forthcoming. 

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_skymap_all_bn231129799.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_healpix_all_bn231129799.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231129799/quicklook/glg_lc_medres34_bn231129799.gif."