GCN Circular 35279

Jia-Cong Liu , Shao-Lin Xiong report on behalf of the GECAM team:

GECAM-B was triggered in-flight by a long burst, GRB 231205B, at 2023-12-05T16:43:34.100 UTC (T0), which was also observed by Swift/BAT (GCN #35269) . 

According to the realtime alert data, the GECAM-B light curve shows roughly two peaks with a total duration of ~40 sec (15-1050 keV). 

The time-averaged spectrum of GECAM-B realtime data from about T0 to T0+4 s could be
adequately fit by a Band function with a fluence about 8.20E-7 erg/cm^2 in 20-1000 keV. 

The GECAM light curve could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231205B_LC.png

GECAM location is consistent with that of Swift/BAT within the error.
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).