Gamma-ray Burst 170522B

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #21130
  K. Hurley, on behalf of the IPN,
  I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova, 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,
  and
  W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
  A long-duration, intense GRB 170522B has been detected by Konus-Wind, Mars-Odyssey (HEND), and INTEGRAL (SPI-ACS), so far, at about 84124 s UT (23:22:04).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

    ---------------------------------------------
     RA(2000), deg                 Dec(2000), deg
    ---------------------------------------------
    Center:
     159.268 (10h 37m 04s) -34.716 (-34d 42' 56")
    Corners:
     158.845 (10h 35m 23s) -35.550 (-35d 32' 58")
     158.818 (10h 35m 16s) -35.346 (-35d 20' 45")
     159.689 (10h 38m 45s) -33.872 (-33d 52' 21")
     159.715 (10h 38m 52s) -34.080 (-34d 04' 47")
    ---------------------------------------------
  

  The error box area is 644 sq. arcmin, and its maximum dimension is 1.82 deg (the minimum one is 6.6 arcmin). The Sun distance was 109 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB170522_T84124/IPN/
  The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #21131
  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/intense GRB 170522B (IPN triangulation: Hurley et al., GCN 21130) triggered Konus-Wind at T0=3D84124.494 s UT (23:22:04.494)
  The burst light curve shows a weak count rate increase (from ~T0-187s to ~T0-167s) followed by a bright, multi-peaked pulse which started at ~T0-30 s an had a total duration of ~87 s. The emission is seen up to ~10 MeV.
  As observed by Konus-Wind, the burst had a fluence of (1.75 =B1 0.11)x10^-4 erg/cm2 and a 64-ms peak energy flux, measured from T0+8.640 s of (2.36 =B1 0.24)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum (measured from T0 to T0+55.040 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 -1.16 (-0.05,+0.06), the high energy photon index beta =3D -2.15 (-0.09,+0.07), the peak energy Ep =3D 252 (-24,+26) keV, chi2 =3D 89/97 dof.
  The spectrum near the peak count rate (measured from T0+8.448 to T0+9.472 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 -0.68 (-0.15,+0.16), the high energy photon index beta =3D -2.29 (-0.31,+0.16), the peak energy Ep =3D 343 (-53,+79) keV, chi2 =3D 75/72 dof.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170522_T84124/
  All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.