[vsnet-grb-info 19622] GRB 170726A: Insight-HXMT detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21366
SUBJECT: GRB 170726A: Insight-HXMT detection
DATE:    17/07/28 06:35:46 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl at ihep.ac.cn>

X. B. Li, J. Y. Liao, C. K. Li, S. L. Xiong, C. Z. Liu, X. F. Li,
Z. W. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang, Y. F. Zhang,
C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU),
F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu, S. N. Zhang (IHEP),
report on behalf of the Insight-HXMT team:

During the commissioning phase, at 2017-07-26T19:02:59.51 (T0),
Insight-HXMT detected GRB 170726A (trigger ID: HEB170726793)
in a routine search of the data, which was also observed by
SPI-ACS (trig time: 2017-07-26T19:02:59.51) and
Fermi/GBM (trig time: 2017-07-26T19:02:59.976).

The Insight-HXMT light curve mainly consists of multi-pulses
with a duration (T90) of 23.7 s measured from T0-5.47 s.
The 1-second peak rate, measured from T0+2 s, is 1364.9 cnts/sec.
The total counts from this burst is 10261.5 counts.

URL_LC: http://www.hxmt.org/images/GRB/HEB170726793_lc.jpg

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.

The time-averaged spectrum from T0-8 s to T0+18 s is
adequately fit by a Power Law model with spectral index = -1.94 +/- 0.05.
The energy fluence is (7.17 +/- 0.38)E-06 erg/cm^2 in 200 - 3000 keV
in this time interval.

The analysis results presented above are preliminary;
final results will be published elsewhere.

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 about it could be found at:
http://www.hxmt.org/index.php/enhome .