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GCN Circular 31240

Subject
GRB 211216A: GECAM detection
Date
2021-12-16T08:22:21Z (2 years ago)
From
Wangchen Xue at IHEP <xuewc@ihep.ac.cn>
W. C. Xue, S. Xiao, Y. Q. Zhang, S. L. Xiong, C. Cai, P. Zhang, 
C. Y. Li, S. L. Xie, X. Y. Zhao, Y. Huang, X. Y. Song,
J. C. Liu,  Y. Zhao, Z. W. Guo, C. Zheng, C. W. Wang, 
Q. B. Yi, B. X. Zhang,  W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, 
X. Ma, L. M. Song, 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, 
H. M. Zhang, Z. H. An, M. Gao, K. Gong, B. Li, C. Li, J. H. Li, 
X. Q. Li, Y. G. Li, X. H. Liang, X. J. Liu, Y. Q. Liu, X. L. Sun, 
Y. L. Tuo, J. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, S. Yang, 
C. Y. Zhang, D. L. Zhang, Fan Zhang, Fei Zhang,
X. Zhou, F. J. Lu, S. N. Zhang (IHEP)
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long burst, 
GRB 211216A, at 2021-12-16T06:45:56.050 UTC (denoted as T0), which was also 
observed by Fermi/GBM (GCN #31237).
 
GECAM alert data was downlinked to the ground through the short message
service of BeiDou Navigation Satellite System (BDS) within ~60 s after T0.

According to the BDS alert data, this burst mainly consists of a broad pulse
with a duration of about 20 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_93336356.png

Using the automatic on-ground localization pipeline with the BDS alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 57.22 deg 
Dec: -63.04 deg
Err: 5.71 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.

GECAM location is consistent with the Fermi/GBM position within the error.

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).
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