TITLE: GCN CIRCULAR NUMBER: 35325 SUBJECT: GRB 231212A: GECAM-C detection of a likely short burst DATE: 23/12/12 03:35:22 GMT FROM: Yue Wang Yue Wang, Shao-Lin Xiong report on behalf of the GECAM team: GECAM-C was triggered in-flight by a likely short burst, GRB 231212A, at 2023-12-12T00:56:48.850 UTC (T0), which was also triggered by Fermi/GBM (TrigNum724035412) . According to the realtime alert data, the GECAM-C light curve shows a short pulse with a duration of ~4 sec (15-1050 keV). The time-averaged spectrum of GECAM-C realtime data from about T0-2 s to T0+2 s could be adequately fit by a cut-off power-law with a flux about 8.01E-7 erg/cm^2/s in 20-1000 keV. Using the automatic on-ground localization pipeline with the realtime alert data, GECAM-C localized this burst to the following position (J2000): Ra: 151.1 deg Dec: -74.1 deg Err: 7.1 deg (1-sigma, statistical only) The GECAM light curve and localization could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/231212A_lc.jpg http://twiki.ihep.ac.cn/pub/GECAM/GRBList/231212A_loc.png We note that these results are based on realtime alert data and thus very preliminary. Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).