Gamma-ray Burst 170424A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #21257
  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 short-duration, hard-spectrum GRB 170616A was detected by Konus-Wind, Mars-Odyssey (HEND), and INTEGRAL (SPI-ACS), at about 57987 s UT (16:06:27).
  We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 113.437 (07h 33m 45s) -2.244 ( -2d 14' 37") Corners: 114.982 (07h 39m 56s) -1.242 ( -1d 14' 32") 114.689 (07h 38m 45s) -1.669 ( -1d 40' 08") 111.834 (07h 27m 20s) -3.158 ( -3d 09' 28") 112.167 (07h 28m 40s) -2.763 ( -2d 45' 46") --------------------------------------------- The error box area is 2500 sq. arcmin, and its maximum dimension is 3.68 deg (the minimum one is 13 arcmin). The Sun distance was 37 deg.
  This box may be improved.
  A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB170616_T57991/IPN
  The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #21258
  D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, P. Oleynik, M. Ulanov, A. Tsvetkova, A. Lysenko, A.Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
  The short-duration GRB 170616A (IPN triangulation: Hurley et al., GCN Circ. 21257) triggered Konus-Wind at T0=57991.385 s UT (16:06:31.385).
  The burst light curve shows a single pulse which starts at ~T0-16 ms and has a total duration of ~42 ms. The emission is seen up to ~10 MeV.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB170616_T57991/
  As observed by Konus-Wind, the burst had a fluence of 3.39(-1.05,+1.14)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0-0.014 s, of 1.14(-0.52,+0.56)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-averaged spectrum of the burst (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.69(-0.31,+0.42) and Ep = 2.5(-1.2,+2.7) MeV (chi2 = 5/7 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.5 (chi2 = 5/6 dof).
  All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.