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GCN Circular 27408

LIGO/Virgo S200316bj: Upper limits from Insight-HXMT/HE observations
2020-03-18T13:39:51Z (4 years ago)
Ce Cai at IHEP <>
C. Cai, W. C. Xue, Y. G. Zheng, Q. Luo, S. Xiao, Q. B. Yi, 
Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, 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:

Insight-HXMT was taking data normally around the reported LIGO/Virgo 
S200316bj event (GCN #27388), trigger time 2020-03-16T21:57:56 UTC. 
At T0, about 74% of the LIGO localization region was covered by the 
Insight-HXMT without occultation by the Earth.

Within T0 +/- 100 s, no significant excess events (SNR > 3 sigma) are 
found in a search of the Insight-HXMT/HE raw light curves.

Assuming the GW counterpart GRB with three typical GRB Band spectral 
models, two typical duration timescales (1 s, 10 s) from the center 
of the LIGO-Virgo location probability map (RA=86 deg, DEC=47 deg), 
the 5-sigma upper limits fluence (0.2 - 5 MeV, incident energy) are 
reported below:

Band model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV):
1 s:   1.1e-07 erg cm^-2
10 s:  4.6e-07 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1 s:   1.9e-07 erg cm^-2
10 s:  6.7e-07 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1 s:   3.0e-07 erg cm^-2
10 s:  1.2e-06 erg cm^-2

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 spacecraft.

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). 
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