{
  "bibcode": "2017GCN.21518....1L",
  "body": "J. Y. Liao, C. K. Li, M. Y. Ge, Y. Huang, Z. W. Li, S. L. Xiong, Y. Liu,\nC. Z. Liu, X. F. Li, Z. Chang, X. F. Lu, J. L. Zhao, A. M. Zhang,\nY. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU),\nT. P. Li (IHEP/THU), F. J. Lu, L. M. Song, H. Y. Wang, M. Wu, Y. P. Xu,\nS. N. Zhang (IHEP), report on behalf of the Insight-HXMT team:\n\nInsight-HXMT was taking data normally around the GBM trigger time\n(T0=2017-08-17 12:41:06.47 UTC) of the short weak bn170817529\n(Connaughton 2017, GCN 21506), which is about 2 seconds after the\nLIGO trigger of G298048 reported in GCN 21505. This GRB was also\ndetected by the INTEGRAL/SPI-ACS (Savchenko 2017, GCN 21507).\n\nAt T0, both the GBM localization error region and the LHV location area\n(reported in GCN 21513) were fully covered by Insight-HXMT\nwithout occultation by the Earth. The incident angle is about 30 deg for\nthe best GBM location (Ra=190.76 deg, Dec=-39.43 deg), corresponding to\nalmost the optimum sensitivity of Insight-HXMT to a GRB.\n\nWithin T0 +/- 1000 s, no significant excess (SNR > 5) was found\nin a search of the Insight-HXMT raw light curves with time scales of\n20 ms, 50 ms, 0.2 s and 1 s, respectively. A 3.2 sigma excess is found\n2 s before T0, however, consistent with background fluctuations.\n\nWith the three typical GRB Band spectral models, integration time of 1 s\nand the best GBM localization, the 3-sigma\nupper-limits of fluence (0.2 - 5 MeV, incident energy) are reported below:\n\nBand model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV):   1.04e-07 erg cm^-2\nBand model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):  1.44e-07 erg cm^-2\nBand model 3 (alpha=0.0, beta=-1.5, Ep=1000 keV):   2.22e-07 erg cm^-2\n\nAll measurements above are made with the CsI detectors operating in the\nregular mode with the energy range of about 80-800 keV (record energy).\nOnly gamma-rays with energy greater than about 200 keV can penetrate\nthe spacecraft and leave signals in the CsI detectors installed inside\nof the telescope.\n\nThe analysis results presented above are preliminary; more analysis results\nwith refined LIGO locations will be reported later.\nIn addition, Insight-HXMT has initiated a ToO observation to the\nGBM location region. ToO observation results will be reported as well.\n\nInsight-HXMT is the first Chinese space X-ray telescope, which was funded\njointly by the China National Space Administration (CNSA) and the Chinese\nAcademy of Sciences (CAS). More information about it could be found at:\nhttp://www.hxmt.org/index.php/enhome .",
  "circularId": 21518,
  "createdOn": 1502998528000,
  "email": "xiongsl@ihep.ac.cn",
  "subject": "LIGO/Virgo G298048: Insight-HXMT observations",
  "submitter": "Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>",
  "eventId": "LIGO/Virgo G298048"
}