{
  "bibcode": "2019GCN.24542....1L",
  "body": "Q. Luo, C. Cai, Q. B. Yi, S. Xiao, C. K. Li, \nX. B. Li, G. Li, J. Y. Liao, S. L. Xiong, \nC. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, \nY. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, \nZ. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, \nM. Wu, Y. P. Xu, S. N. Zhang (IHEP), \nreport on behalf of the Insight-HXMT team: \n\nInsight-HXMT was taking data normally around the reported LIGO/Virgo \nS190513bm event (GCN #24522), trigger time T0=2019-05-13 20:54:28.747 \nUTC. At T0, about 42% of the LIGO localization region was covered by \nInsight-HXMT without occultation by the Earth.\n\nBy searching the Insight-HXMT/HE raw light curves within T0 +/- 100 s, \nwe found that there is one excess with a significance of 4.3 sigma from \nT0 + 8.50 s to T0 + 8.65 s. After an initial investigation, we believe \nthat this signal is very likely due to background fluctutations and thus \nunrelated to the GW event.\n\nAssuming the GW counterpart GRB with three typical GRB Band spectral \nmodels, two typical duration timescales(1 s, 10 s) from the peak \nposition of the LIGO-Virgo location probability map, the 5-sigma \nupper-limits fluence (0.2 - 5 MeV, incident energy) are reported below:\n\nBand model 1 (alpha=-1.9, beta=-3.7, Ep=70 keV):\n1 s:   2.8e-07 erg cm^-2\n10 s:  1.1e-06 erg cm^-2\n\nBand model 2 (alpha=-1.0, beta=-2.3, Ep=230 keV):\n1 s:   4.0e-07 erg cm^-2\n10 s:  1.8e-06 erg cm^-2\n\nBand model 3 (alpha=-0.0, beta=-1.5, Ep=1000 keV):\n1 s:   5.3e-07 erg cm^-2\n10 s:  2.8e-06 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 (deposited 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.",
  "circularId": 24542,
  "createdOn": 1557848438000,
  "email": "luoqi@ihep.ac.cn",
  "subject": "LIGO/Virgo  S190513bm: Insight-HXMT/HE observation",
  "submitter": "Qi Luo at IHEP  <luoqi@ihep.ac.cn>"
}