GCN Circular 24077

Q. Luo, C. Cai, 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 GW trigger time
(T0=2019-04-08 18:18:02.288 UTC). At T0, the LIGO-Virgo localization 
region was fully covered by the Insight-HXMT without occultation
by the Earth.

Within T0 �� 100 s, no significant excess events (SNR > 5 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 peak 
position of the LIGO-Virgo location probability map, 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):
1s:   1.6e-08 erg cm^-2
10s:  5.3e-08 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1s:   2.6e-08 erg cm^-2
10s:  8.7e-08 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1s:   7.1e-08 erg cm^-2
10s:  2.9e-07 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 (record 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 
fundedjointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information could be found at: http://www.hxmt.org.