TITLE:   GCN CIRCULAR
NUMBER:  29737
SUBJECT: GRB 210328A: GECAM detection
DATE:    21/03/30 15:38:19 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

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

During the commissioning phase, GECAM-B triggered by a long burst,
GRB 210328A, at 2021-03-28 20:45:17.900 UTC (T0), which was also detected
by Fermi/GBM (GCN #29732)

According to the GECAM-B light curves in about 20 keV - 500 keV,
this burst mainly consists of a broad pulse with duration of about 12 s.

Spectral evolution is clearly seen during the burst, and the emissions
in low energies last longer than that in high energies.

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: 201.9 deg Dec: -2.6 deg
Err: 3.4 deg (1-sgima, 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 and BALROG positions
within the error.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/multiLCvsE_tn210328_204626.pdf

The GECAM preliminary location could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/tn210328_204626_locSatB.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).