Gamma-ray Burst 120426A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #13265
  K. Hurley, and J. Goldsten, on behalf of the MESSENGER NS 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,
  V. Connaughton, M. Briggs, and C. Meegan, on behalf of the Fermi GBM team,
  S. Barthelmy, J. Cummings, N. Gehrels, H. Krimm, and D. Palmer, on behalf of the Swift-BAT 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 GRB 120426A has been observed by Fermi (GBM: trigger 357098956), INTEGRAL (SPI-ACS), Konus-Wind, MESSENGER (GRNS), and Swift (BAT), so far, at about 7754 s UT (02:09:14). 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:
     111.537 (07h 26m 09s) -65.631 (-65d 37' 53")
    Corners:
     111.594 (07h 26m 23s) -66.533 (-66d 31' 58")
     111.041 (07h 24m 10s) -65.195 (-65d 11' 41")
     111.487 (07h 25m 57s) -64.732 (-64d 43' 56")
     112.050 (07h 28m 12s) -66.066 (-66d 03' 59")
    ---------------------------------------------
  

  The error box area is 0.355 sq. deg, and its maximum dimension is 1.8 deg.
  This box may be improved.
  The time history and spectrum will be given in a forthcoming GCN Circular.
• GCN Circular #13266
  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 bright GRB 120426A (IPN localization: Hurley at al., GCN 13265) triggered Konus-Wind at T0=07755.610s UT (02:09:15.610)
  The light curve shows a broad pulse with a total duration of ~3.2 s. The emission is seen up to ~8 MeV and displays a noticeable hard-to-soft spectral evolution. A spectral lag between the hard G3(1400-300 keV) and the soft G1(25-90 keV) instrument's light curves is estimated to 0.57 � 0.8 s (1 sigma).
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB120426_T07755/
  As observed by Konus-Wind the burst had a fluence of (1.9 � 0.1)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.344 s, of (1.3 � 0.2)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum of the burst (measured from T0 to T0+2.048 s) is best fitted in the 20 keV - 10 MeV range with the GRB (Band) model, for which: the low-energy photon index alpha = -0.61 (-0.10, +0.11), the high energy photon index beta = -3.2 (-0.4, +0.2), the peak energy Ep = 140(-8, +7) keV, chi2 = 84.8/81 dof.
  All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.
• GCN Circular #13268
  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 bright GRB 120426A (IPN localization: Hurley at al., GCN 13265) triggered Konus-Wind at T0=3D07755.610s UT (02:09:15.610)
  The light curve shows a broad pulse with a total duration of ~3.2 s. The emission is seen up to ~8 MeV and displays a noticeable hard-to-soft spectral evolution. A spectral lag between the hard G3(1400-300 keV) and the soft G1(25-90 keV) instrument's light curves is estimated to 0.57 =B1 0.08 s (1 sigma).
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB120426_T07755/
  As observed by Konus-Wind the burst had a fluence of (1.9 =B1 0.1)x10-5 erg/cm2, and a 64-ms peak flux, measured from T0+1.344 s, of (1.3 =B1 0.1)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
  The time-integrated spectrum of the burst (measured from T0 to T0+2.048 s) is best fitted in the 20 keV - 10 MeV range with the GRB (Band) model, for which: the low-energy photon index alpha = -0.61 (-0.10, +0.11), the high energy photon index beta = -3.2 (-0.4, +0.2), the peak energy Ep = 140(-8, +7) keV, chi2 = 84.8/81 dof.
  All the quoted results are preliminary. All the quoted errors are at the 90% confidence level.