GCN Circular 34630
Shaolin Xiong, Wangchen Xue, Yue Huang report on behalf of the GECAM team: GECAM-C was triggered in-flight by a long burst, GRB 230905B, at 2023-09-05T15:49:35.850, which was also observed by INTEGRAL/SPI-ACS. According to the realtime alert data of GECAM-C, this burst mainly consists of a long pulse with a duration (T90) of about ~10 sec (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: 340.1 deg DEC: 9.2 deg Err: 5.2 deg (1-sigma, statistical only) The systematic error of this location is estimated to be several degrees. The time-averaged spectrum of GECAM-C realtime data shows that it could be adequately fit by a cut-off power-law with a fluence about 2.7E-6 erg/cm^2 in 20-1000 keV. We note that these results are based on realtime alert data and thus very preliminary. Refined analysis will be reported later. 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).