GRB 211223A

GRB 211223A: GECAM detection

X. L. Zhang, W. C. Xue, S. Xiao, Y. Q. Zhang, S. L. Xiong, C. Cai, 
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, P. 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 211223A, at 2021-12-23T02:41:18.900 UTC (denoted as T0)
, which was also observed by CALET/GBM.
 
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 40 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/211223Alc.png

Using the automatic on-ground localization pipeline with the BDS alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra:  320.20 deg 
Dec: -30.74 deg
Err: 4.45 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 preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/211223Alocation.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).

X.L.Zhang, Y. Q. Zhang, S. L. Xiong, X. B. Li, C. Cai, Q. Luo, 
S. Xiao, J. C. Liu, W. C. Xue, Q. B. Yi, C. Zheng���Y. Huang,
G. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu,  C. K. Li, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-12-23T02:40:35.450 (T0), Insight-HXMT/HE detected 
GRB 211223A (trigger ID: HEB211223111) in a routine search of the data, 
which also triggered GECAM (GECAM Team, GCN #31286
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 ) and CALET.

URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB211223111lc.png

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.