TITLE:   GCN CIRCULAR
NUMBER:  30696
SUBJECT: GRB 210822A: GECAM refined analysis
DATE:    21/08/23 15:00:34 GMT
FROM:    Chenwei Wang at IHEP  <cwwang@ihep.ac.cn>

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

At 2021-08-22T09:18:18.00 UTC(denoted as T0), GECAM-B was triggered in-flight 
by a long bright burst, GRB 210822A, which is also observed by Swift/BAT (GCN #30677). 
The spectrum was calculated using the GECAM-B trigger data. 

The time-integrated spectrum (measured from T0 to T0+15) 
is best fit in the 20 keV - 5 MeV range 
by a power law with high energy exponential rolloff model:
dN/dE ~ (E^alpha)*exp(-E/beta)
with  alpha = -0.8595 +/- 0.029,
and beta = 394.9867 +/- 23.466 keV.

The event fluence (10-1000 keV) in this time interval is
(7.54 +0.10/-0.19)E-05 erg/cm^2. 

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).