TITLE:   GCN CIRCULAR
NUMBER:  22149
SUBJECT: GRB 171120A: Insight-HXMT detection
DATE:    17/11/23 15:03:23 GMT
FROM:    Zhengwei Li at IHEP  <lizw@ihep.ac.cn>

Z. W. Li, J. Y. Liao, C. K. Li, X. B. Li, S. L. Xiong, C. Z. Liu, 
X. F. 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 2017-11-20T13:20:02.00 (T0),
Insight-HXMT detected GRB 171120A (trigger ID: HEB171120555)
in a routine search of the data, which was also observed by
Swift/BAT (A. Tohuvavohu et al, GCN Circ.22133), Swift/XRT(P.A. Evans 
et al, GCN Circ.22135),Fermi/GBM(M.Stanbro et al, GCN Circ.22138),


Fermi/LAT(F. Longo et al, GCN Circ.22136), Konus-Windan(D.Frederiks

et al, GCN Circ.22142) and AstroSat/CZTI (V.Sharma et al, GCN Circ.22143).




The Insight-HXMT light curve consists of two pulses with a duration (T90)

of 39.9s measured from T0+0.5s. The 200-ms peak rate, measured from 

T0+0.6s, is 6895.7 cnts/sec. The total counts from this burst is 5746.9 

counts.


URL_LC: http://www.hxmt.org/images/GRB/HEB171120555_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 T0-0.2 to T0+1.0 s is adequately fit by 

a Power Law model with spectral index = -1.96 +/- 0.07 . The energy fluence

is (6.20 +/- 0.33) E-06 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 .