TITLE: GCN CIRCULAR NUMBER: 33407 SUBJECT: GRB 230307A: Fermi GBM detection of a very bright GRB DATE: 23/03/07 17:10:32 GMT FROM: Sarah Dalessi at UAH S. Dalessi(UAH) report on behalf of the Fermi GBM Team: "At 15:44:06.67 UT on 07 March 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230307A (trigger 699896651 / 230307656). This event is one of the brightest among the GBM detected GRBs. Follow-up across all wavelengths is encouraged. The on-ground calculated location, using the GBM trigger data, is RA = 54.06, DEC = -76.61 (J2000 degrees, equivalent to J2000 03h 36m, -76d 35'), with a statistical uncertainty of 1 degrees (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 at the GBM trigger time is 142.0 degrees. A full GCN of the Fermi-GBM analysis of this event will follow in a later GCN, once the data has become available. For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"