Gamma-ray Burst 180113

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #22329
  P. Veres and C. Meegan (both UAH) report on behalf of the Fermi GBM Team:
  "At 00:16:00.47 UT on 13 January 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 180113B (trigger 537495365 / 180113011).
  The on-ground calculated location, using the GBM trigger data, is RA = 354.0, DEC = 13.5 (J2000 degrees, equivalent to 23 h 36 m, 13 d 28 '), with an uncertainty of 1.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).
  The angle from the Fermi LAT boresight at the GBM trigger time is 88 degrees.
  The GBM light curve consists of multiple pulses with a duration (T90) of about 15.9 s (50-300 keV). The time-averaged spectrum from T0-5.6 s to T0+17.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.95 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 670 +/- 41 keV.
  A Band function fits the spectrum equally well with Epeak = 647 +/- 46 keV, alpha = -0.95 +/- 0.02, and beta = -2.70 +/- 0.37.
  The event fluence (10-1000 keV) in this time interval is (1.539 +/- 0.017)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+3.2 s in the 10-1000 keV band is 36.9 +/- 0.5 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #22342
  C. K. Li, S. L. Xiong, X. B. Li, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, J. L. Zhao, A. M. Zhang, Y. F. Zhang, X. F. Lu, 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:
  At 2018-01-13T00:16:00.00 UT (T0), the Insight-HXMT/HE detected GRB 180113B(trigger ID: HEB180113011) in a routine search of the data, which was also triggered by Fermi/GBM (Veres et al. GCN 22329) and INTEGRAL/SPI-ACS.
  The Insight-HXMT light curve consists of multiple pulses with a duration (T90) of 11.7 s measured from T0+1.06 s. The 1-s peak rate, measured from T0+1.30 s, is 13236.7 cnts/sec. The total counts from this burst is 31306.5 counts.
  URL_LC: http://www.hxmt.org/images/GRB/HEB180113011_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 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 .
  
• GCN Circular #22354
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, and T. Cline on behalf of the Konus-Wind team,
  K. Hurley, on behalf of the IPN,
  V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team, and
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, report:
  The bright long-duration GRB 180113B (Veres and Meegan, GCN Circ. 22329) was detected by Fermi (GBM trigger 537495365), Konus-Wind, and INTEGRAL (SPI-ACS) at about 960 s UT (00:16:00).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

    ---------------------------------------------
     RA(2000), deg                 Dec(2000), deg
    ---------------------------------------------
    Center:
       6.697 (00h 26m 47s) +24.021 (+24d 01' 15")
    Corners:
       3.866 (00h 15m 28s) +27.572 (+27d 34' 20")
       8.260 (00h 33m 03s) +22.591 (+22d 35' 29")
       7.772 (00h 31m 05s) +22.219 (+22d 13' 07")
       3.373 (00h 13m 29s) +27.185 (+27d 11' 07")
    ---------------------------------------------
  

  The error box area is 3.7 sq. deg, and its maximum dimension is 6.4 deg (the minimum one is 35 arcmin). The Sun distance was 82 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB180113_T00958/IPN
  The Konus-Wind time history and spectrum will be given a forthcoming GCN Circular.
• GCN Circular #22355
  D. Frederiks, S. Golenetskii, R.Aptekar, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, A. Kozlova, and T. Cline, on behalf of the Konus-Wind team, report:
  The long GRB 180113B (Fermi-GBM detection: Veres & Meegan, GCN 22329; Insight-HXMT/HE observation: Li et al., GCN 22342; IPN Triangulation: Svinkin et al., GCN 22354) triggered Konus-Wind at T0=3D958.621 s UT (00:15:58.621).
  The KW light curve shows a multiple pulses in the interval from ~T0 to ~T0+20 s. The emission is seen up to ~10 MeV.
  As observed by Konus-Wind, the burst had a fluence of (4.05 =B1 0.29)x10^-5 erg/cm2 and a 64-ms peak energy flux, measured from T0+3.200 s, of (2.2 =B1 0.1)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+20.224 s) is best fit in the 20 keV - 15 MeV range by a cutoff power-law (CPL) function with the following model parameters: the photon index alpha =3D -0.97(-0.07,+0.08), and the peak energy Ep =3D 559(-58,+71) keV, chi2 =3D 81/98 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and an upper limit on beta of ~-2.0.
  The spectrum near the peak count rate (measured from T0 to T0+3.840 s) is best fit in the 20 keV - 15 MeV range by the CPL function with the following model parameters: the photon index alpha =3D -0.80(-0.06,+0.06), and the peak energy Ep =3D 611(-47,+53) keV, chi2 =3D 93/98 dof. Fitting this spectrum with the GRB (Band) function yields the same alpha and Ep, and an upper limit on beta of ~-2.0.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB180113_T00958/
  All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
• GCN Circular #22364
  V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration:
  Analysis of Astrosat CZTI data showed the detection of bright GRB 180113B, which was also detected by Fermi-GBM (Veres P. et al., GCN 22329), Insight-HXMT/HE (Li C. K. et al., GCN 22342), IPN Triangulation (Svinkin D. et al., GCN 22354) and Konus-Wind (Frederiks D. et al., GCN 22355).
  The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 00:16:01.500 UT, ~1 s after the Fermi-GBM trigger. The measured peak count rate is 1344.6 cts/s above the background in combined data of four quadrants, with a total of 3534 cts. The local mean background count rate was 520 cts/s. Using cumulative rates, we measure a T90 of 10.8 s.
  It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.
  CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.