Gamma-ray Burst 131216A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #15598
  P. Veres (Penn State), D. Kocevski (NASA/Goddard), E. Bissaldi (University & INFN Trieste), R. Desiante (University of Udine and INFN Trieste), J. Racusin (NASA/Goddard), report on behalf of the Fermi-LAT team:
  The Fermi Large Area Telescope (LAT) detected emission from GRB 131216A, also detected by GBM (trigger 408851795/131216081) at T0 = 01:56:32.06 UT on December 16, 2013.
  The GBM location was initially inside the LAT field of view at an angle of 44 degrees to the LAT boresight and triggered an autonomous repoint of the spacecraft. However, LAT did not collect data while in the South Atlantic Anomaly (SAA) from T0+200 to T0+800 s. No significant excess is seen using standard analysis procedures.
  Using the LAT Low Energy (LLE) event selection, over 120 counts above background were detected within a 0.3 s interval coinciding with the time of the GBM emission. This data selection has insufficient spatial resolution to provide a reliable LAT localization. Since an excess of events were not seen using the standard analysis selection, this detection is likely due to low energy gamma-rays (below 100 MeV).
  The Fermi LAT point of contact for this burst is Peter Veres (puv2@psu.edu).
  The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.
• GCN Circular #15599
  V. Pelassa (UAH) reports on behalf of the Fermi GBM Team:
  "At 01:56:32.06 UT on 16 December 2013, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 131216A (trigger 408851795 / 131216081). It was also detected by the Fermi Large Area Telescope (Veres et al 2013, GCN 15598).
  The on-ground calculated location, using the GBM trigger data, is RA = 91.6, DEC = -35.5 (J2000 degrees, equivalent to +06h 06m, -35d 30'), with an uncertainty of 2.7 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The angle from the Fermi LAT boresight was 44 degrees at trigger time, then an autonomous repoint maneuver placed the GRB near the center of the LAT field-of-view.
  This burst was also independently detected by INTEGRAL SPI-ACS.
  The GBM light curve consists of a single FRED pulse with a duration (T90) of about 24 s (50-300 keV). The time-averaged spectrum from T0-0.256 s to T0+11.264 s, when the flux is highest, is best fit by a Band function with Epeak = 359 +/- 40 keV, alpha = -0.64 +/- 0.07, and beta = -2.03 +/- 0.13 (Castor statistics 777.70 for 716 d.o.f.).
  The event fluence (10-1000 keV) in this time interval is (8.60 +/- 0.20)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0+0.512 s in the 10-1000 keV band is 7.9 +/- 0.2 ph/s/cm^2.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #15600
  K. Hurley and J. Goldsten, on behalf of the MESSENGER NS GRB team,
  S. Golenetskii, R. Aptekar, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
  K. Yamaoka, M. Ohno, Y. Hanabata, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima, on behalf of the Suzaku WAM team,
  S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team, and
  V. Connaughton, M. S. Briggs, C. Meegan, V. Pelassa, and A. Goldstein, on behalf of the Fermi GBM team, report:
  The long-duration GRB 131216A (V. Pelassa GCN Circ. 15599; P. Veres et al. GCN Circ. 15598) was observed by Fermi (GBM: trigger 408851795), Konus-Wind, INTEGRAL (SPI-ACS), Swift (BAT), Suzaku (WAM), and MESSENGER (GRNS) at about 6992 s UT (01:56:32). The burst was outside the coded field of view of the BAT.
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

      ---------------------------------------------
       RA(2000), deg                 Dec(2000), deg
      ---------------------------------------------
      Center:
        94.674 (06h 18m 42s) -41.627 (-41d 37' 35")
      Corners:
        88.596 (05h 54m 23s) -43.014 (-43d 00' 51")
        99.822 (06h 39m 17s) -40.204 (-40d 12' 16")
       100.505 (06h 42m 01s) -39.743 (-39d 44' 34")
        89.379 (05h 57m 31s) -42.669 (-42d 40' 08")
      ---------------------------------------------
  

  The error box area is 1.8 sq. deg, and its maximum dimension is 9.5 deg (the minimum one is 0.2 deg).
  The center of the GBM ground position (V. Pelassa GCN Circ. 15599) is 6.58 deg from the center of the box.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB131216_T06993/IPN/
• GCN Circular #15611
  T. Nagayoshi, M. Tashiro, Y. Terada, S. Koyama, T. Yasuda, S. Takeda, Y. Ishida, H. Ueno, S. Sugimoto (Saitama U.), M. Yamauchi, N. Ohmori, M. Akiyama, R. Kinoshita (Univ. of Miyazaki), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.), K. Yamaoka (Nagoya U.), S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), W. Iwakiri(RIKEN), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:
  The GRB 131216A (Fermi LAT detection: Veres et al.,GCN Circ. 15598, IPN localization:Hurley et al., GCN Circ. 15600) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 01:56:32.11 UT (=T0).
  The observed light curve shows a single FRED-like peak starting at T0-1 s, ending at T0+8s, with a duration T90 of 5.69 seconds. The fluence in 100 - 1000 keV was 7.46 (+0.99/-0.86) x10^-6 erg/cm^2. The 1-s peak flux measured from T0+2s was 6.05 (+0.50/-0.73) photons/cm^2/s in the same energy range.
  Preliminary result shows that the time-averaged spectrum fromT0-1s to T0+8s is well fitted by a power-law with exponential cutoff model:

      dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
      alpha 1.42(+0.05/-0.73), and
      Epeak 400(+135/-142) keV (chi^2/d.o.f. = 15.5/13).
  

  All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included.The light curves for this burst will be available at:
  http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html