GCN Circular 30874

GRB 210923B: GECAM detection

X. L. Zhang, S. L. Xiong, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai,
S. Xiao, S. L. Xie, Y. Q. Zhang, Y. Zhao, Z. W. Guo, C. Zheng, 
W. C. Xue, C. Y. Li, C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang,
W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, X. Ma, P. Wang, J. Wang, 
Z. Zhang, S. J. Zheng, W. Chen, J. J. He, G. Y. Zhao, Y. Q. Du,
H. Wu, J. Liang, Q. Luo, J. C. Liu, 
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered ground by a short
bright burst, GRB 210923B, at 2021-09-23 02:11:29.000 UTC (denoted as T0),
which was also detected by Konus-Wind.
According to the GECAM-B light curves in about 15-3500 keV, this 
burst mainly consists of a broad pulse with a duration of about 0.679 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210923_021129_GECAMb_lc.png

GECAM-B localized this burst to the following position (J2000):
Ra: 287.25 deg 
Dec: -12.03 deg
Err: 6.29 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).