[vsnet-grb-info 27276] GRB 210131A: GECAM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29379
SUBJECT: GRB 210131A: GECAM detection
DATE:    21/02/02 09:48:28 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo at ihep.ac.cn>

S. Xiao, C. Cai, S. L. Xiong, Y. Huang, Y. Zhao, C. Y. Li, J. C. Liu,
J. J. He, Q. B. Yi, B. X. Zhang, Y. Q. Zhang, S. Y. Zhao, C. Zheng,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, B. Li,
C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, W. C. Xue, S. Yang, M. Yao,
C. Y. Zhang,D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang,
P. Zhang, S. N. Zhang, Z. Zhang, X. Y. Zhao, S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, the ground search of GECAM-B data found
a long burst, GRB 210131A, at 2021-01-31T12:29:12.000 UTC (T0).

According to the GECAM-B light curves in about 8 keV-4 MeV, this burst
mainly consists of a broad pulse with a duration (T90) of 8.7 +/- 0.4 s.
The 1-s peak counts rate is about 591 cps while the total counts is about
3814 counts.

Although the in-flight calibration of energy response and
localization has not been finalized yet, GECAM-B localized this burst to
the following position (J2000):

Ra: 35.17 deg Dec: 25.23 deg
Err: 7.39 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.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210131_122912_GECAMb_v0.pdf

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).