TITLE:   GCN CIRCULAR
NUMBER:  21301
SUBJECT: GRB 170705A: Insight-HXMT observation
DATE:    17/07/06 18:10:53 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

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

During the commissioning phase, at 2017-07-05T02:45:59.00 (T0),
Insight-HXMT detected GRB 170705A (trigger ID: HEB170705115)
in a routine search of the data, which was also observed by
the Swift/BAT (Starling et al. 2017, GCN 21289), Fermi/GBM
(Bissaldi et al. 2017, GCN 20297) and Konus-Wind (Svinkin et al. 2017,
GCN 21299).

The Insight-HXMT light curve consists of single pulse
with a duration (T90) of 7.0 s measured from T0-1.30 s.
The 1-second peak rate, measured from T0+1 s, is 928.3 cnts/sec.
The total counts from this burst is 3458 counts.

All measurements above are made with the CsI detectors in the energy range
of about 80-840 keV (record energy) in the regular mode. Only gamma-rays 
with
energy greater than about 200 keV can penetrate the spacecraft and leave
signals in the CsI detectors installed on the inside of the telescope.

URL_LC: http://www.hxmt.org/images/GRB/HEB170705115_lc.jpg

The time-averaged spectrum from T0-2 s to T0+8 s is
adequately fit by a Power Law model with spectral index = -2.16 +/- 0.10.
The energy fluence is (1.42 +/- 0.30)E-05 erg/cm^2 in 200 - 5000 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 .