Gamma-ray Burst 130521B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #14696
  K. Hurley, I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  J. Goldsten, on behalf of the MESSENGER NS GRB team,
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, and
  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, report:
  The long-duration, moderately intense GRB 130521B has been observed by Konus-Wind, Suzaku (WAM), MESSENGER (GRNS), and Mars Odyssey (HEND), so far, at about 77073 s UT (21:24:33).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

    ---------------------------------------------
     RA(2000), deg                 Dec(2000), deg
    ---------------------------------------------
    Center:
     281.641 (18h 46m 34s) +22.723 (+22d 43' 21")
    Corners:
     281.980 (18h 47m 55s) +22.385 (+22d 23' 05")
     281.618 (18h 46m 28s) +22.858 (+22d 51' 30")
     281.300 (18h 45m 12s) +23.057 (+23d 03' 24")
     281.663 (18h 46m 39s) +22.587 (+22d 35' 13")
    ---------------------------------------------
  

  The error box area is 257 sq. arcmin, and its maximum dimension is 55 arcmin (the minimum one is 3.7 arcmin). The Sun distance was 120 deg.
  This box can be improved.
  The time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #14698
  S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
  The long-duration GRB 130521B (IPN triangulation: Hurley at al., GCN 14696) triggered Konus-Wind at T0=3D77073.510s UT (21:24:33.510).
  The light curve shows several pulses from ~T0 s to ~T0+20s, which, at its initial phase, form a quasi-periodic structure with the period of ~2.5s. The emission is seen up to ~7 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130521_77073/
  As observed by Konus-Wind, the burst had a fluence of (1.9 =B1 0.15)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.512s, of (4.3 =B1 0.3)x10-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+22.016 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.96 =B1 0.07, the high energy photon index beta =3D -2.9 =B1 0.3, the peak energy Ep =3D 151 =B1 9 keV, chi2 =3D 97.6/97 dof.
  The spectrum at the maximum count rate (measured from T0 to T0+5.888 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha =3D -0.69 =B1 0.08, the high energy photon index beta =3D -3.6 =B1 1.1, the peak energy Ep =3D 205 =B1 12 keV, chi2 =3D 107/97 dof.
  For both spectra, we note a hint of counts excess over the model flux in the spectral channels around ~10 MeV.
  All the quoted results are preliminary.
• GCN Circular #14700
  W. Iwakiri(RIKEN), M. Tashiro, Y. Terada, T. Yasuda, Y. Ishida, H. Ueno, S. Sugimoto (Saitama U.), M. Ohno, K. Takaki, T. Kawano, R. Nakamura, S. Furui, Y. Fukazawa (Hiroshima U.), M. Yamauchi, N. Ohmori, M. Akiyama (Univ. of Miyazaki), K. Yamaoka (Nagoya U.), S. Sugita (Ehime U.), Y. E. Nakagawa, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. Hanabata (ICRR), Y. Urata (NCU), K. Nakazawa, K. Makishima (Univ. of Tokyo) on behalf of the Suzaku WAM team, report:
  The long, IPN localized GRB 130521B (Hurley et al., GCN 14696; Konus-Wind detection : Golenetskii et al., GCN 14698) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 21:24:31.599 UT (=T0).
  The observed light curve shows a multi-peaked structure starting at T0-0s, ending at T0+25 s with a duration (T90) of about 23 seconds. The fluence in 100 - 1000 keV was 1.21 (+0.07/-0.08) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+1 s was 4.25 (+1.63/-0.54) photons/cm^2/s in the same energy range.
  Preliminary result shows that the time-averaged spectrum from T0-0s to T0+25 s is well fitted by a single power-law with a photon index of 2.33 (+0.19/-0.16) (chi^2/d.o.f = 30.0/25).
  All the quoted errors are at statistical 90% confidence level,in which the systematic uncertainties are not included.
  The light curves for this burst are available at:
  http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html