GRB 231206A: GECAM-B detection of a short burst

GECAM-B was triggered in-flight by a short burst, GRB 231206A, at 2023-12-06T02:37:43.250 UTC (T0), which was also observed by INTEGRAL/SPI-ACS . According to the realtime alert data, the GECAM-B light curve shows a peak with a total duration of ~0.5 sec (15-1050 keV). The time-averaged spectrum of GECAM-B realtime data from about T0 to T0+0.1 s could be adequately fit by a cut-off power-law with a fluence about 6.04E-6 erg/cm^2 in 20-1000 keV. Using the automatic in-flight localization pipeline with the realtime alert data, GECAM-B localized this burst to the following position (J2000): RA: 313.15 deg DEC: -23.54 deg Err: 8.0 deg (1-sigma, statistical only) The systematic error of this location is estimated to be several degrees. The GECAM light curve could be found here: http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB231206A_LC.png 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).