GCN Circular 24651

C. Cai, S. Xiao, Q. B. Yi, Q. Luo, C. K. Li, 
X. B. Li, G. 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 
S190521g event (GCN #24621
Not found
 
 
), trigger time 2019-05-21T03:02:29 UTC. 
At T0, more than 34% of the LIGO localization region was covered by 
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=340 deg, DEC=-50 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:   1.2e-07 erg cm^-2
10 s:  5.7e-07 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1 s:   1.7e-07 erg cm^-2
10 s:  7.2e-07 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1 s:   3.2e-07 erg cm^-2
10 s:  1.4e-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). 
More information could be found at: http://www.hxmt.org.