TITLE:   GCN CIRCULAR
NUMBER:  34401
SUBJECT: GRB 230812B: GECAM-C observation of a very bright burst
DATE:    23/08/13 09:31:23 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

Shaolin Xiong, Jiacong Liu, Yue Huang report on behalf of the GECAM team:

GECAM-C was triggered in-flight by a very bright burst, GRB 230812B, at 2023-08-12T18:58:12.100 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM Team, GCN 34386), Fermi/LAT (Scotton et al, GCN 34392), etc. Both the GECAM-C in flight location and on-ground location are generally consistent with the Fermi/GBM within error.

According to the realtime alert data, the GECAM-C light curve shows a FRED shape with a duration (T90) of ~4 sec (6-1000 keV). The time-averaged spectrum shows that it could be adequately fit by a Band function with a fluence about 2E-4 erg/cm2 in 20-1000 keV. We note that this analysis is 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).