GCN Circular 24388

Q. B. Yi, Q. Luo, C. Cai,S. Xiao , 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 HEN trigger time
(T0=2019-05-03 17:23:08  UTC). At T0, about 100% 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 HEN 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: 1.8e-07 erg cm^-2
10s: 6.1e-07 erg cm^-2

Band model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):
1s: 2.7e-07 erg cm^-2
10s: 9.7e-07 erg cm^-2

Band model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):
1s: 4.6e-07 erg cm^-2
10s: 2.2e-06 erg cm^-2
Further analysis will be reported in the following circulars.

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.