GCN Circular 30922

Y. Q. Zhang, S. L. Xiong, S. Xiao, C. Cai, X. Y. Zhao, Y. Huang, X. Y. Song,
J. C. Liu, S. L. Xie,  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, X. L. Zhang,
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered on-ground by
a bright short burst from SGR J1555.2-5402 at 2021-10-04T00:13:14.700 UTC (T0).

According to the GECAM-B light curves in about 10-50 keV, this burst mainly
consists of a single pulse with a duration about 30 ms.The location given by 
GECAM-B alone is consistent with SGR J1555.2-5402 within the error.

GECAM-B localized this burst to the following position (J2000): 
Ra: 241.96 deg 
Dec: -55.45 deg
Err: 9.01 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/utn211004_001314_GECAMb.png

According to our multiple-mission joint location pipeline (S. Xiao et al.,
accepted by ApJ) using GECAM-B and Fermi/GBM data, this burst is localized to
an annulus which is very consistent with SGR J1555.2-5402. 

The GECAM-GBM joint location could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/SGR20211004T001314.700-JointLoc.png

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).