Gamma-ray Burst 070402

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #6241
  K. Hurley and T. Cline, on behalf of the Mars Odyssey, Konus, and MESSENGER GRB teams,
  I. Mitrofanov, A. Kozyrev, M. Litvak, A. Sanin, V. Tret'yakov and A. Parshukov, on behalf of the HEND-Odyssey GRB team,
  W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team,
  S. Golenetskii, R. Aptekar, E. Mazets, V. Pal'shin, and D. Frederiks, on behalf of the Konus-Wind team,
  D. M. Smith, R. P. Lin, J. McTiernan, R. Schwartz, C. Wigger, W. Hajdas, and A. Zehnder, on behalf of the RHESSI GRB team,
  A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS GRB team, and
  K. Yamaoka, E. Sonoda, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, and K. Makishima, on behalf of the Suzaku WAM GRB team, report:
  Konus-Wind, Suzaku-WAM, INTEGRAL SPI-ACS, Mars Odyssey, and RHESSI observed the long-duration, hard spectrum GRB070402 at 56915 s. As observed by Konus, it had a duration ~12 s, a fluence ~10^-5 erg cm^-2, and an Epeak~350 keV. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:

     RA(2000)                    Dec(2000)
  
  Center:
   311.184 (20h 44m 44s)   +27.404 (+27d 24' 14")
  Corners:
   310.481 (20h 41m 55s)   +26.971 (+26d 58' 16")
   310.516 (20h 42m 04s)   +27.237 (+27d 14' 14")
   311.893 (20h 47m 34s)   +27.822 (+27d 49' 20")
   311.854 (20h 47m 25s)   +27.560 (+27d 33' 36")
  

  The error box area is ~0.3 square arcminutes.
  MESSENGER data have not yet been downlinked; when they become available, it may be possible to reduce the size of this error box considerably.
• GCN Circular #6023
  K. Hurley reports:
  In GCN 6241, the area of the error box should be ~0.3 square degrees, not square arcminutes. (Thanks to Alex Kann for pointing this out.)
  I regret any confusion which this may have caused.
• GCN Circular #6243
  S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and T. Cline on behalf of the Konus-Wind and Konus-A teams report:
  The long GRB 070402 (Hurley et al., GCN 6241, 6242), triggered Konus-Wind at T0=56914.653 s UT (15:48:34.653). Konus-A observed this GRB in the waiting mode.
  The Konus-Wind light curve shows a single multipeaked pulse with a total duration of ~12 s. As observed by Konus-Wind the burst had a fluence of 1.17(-0.22, +0.06)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+3.184 s 3.18(-0.72, +0.42)x10^-6 erg/cm2/s (both in the 20 keV - 3 MeV energy range).
  The spectrum of the most intense part integrated from T0 to T0+8.192 s (this interval comprises ~90% of the burst total counts) is well fitted (in the 20 keV - 3 MeV range) by a power law with exponential cutoff model: dN/dE ~ E^(-alpha) * exp(-(2-alpha)*E/Ep) with alpha = 0.92(-0.12, +0.11) and Ep = 325(-40, +52) keV (chi2 = 60/68 dof).
  All the quoted errors are at the 90% confidence level.
  The Konus-Wind light curve of this GRB is available at http://www.ioffe.rssi.ru/LEA/GRBs/GRB070402_T56914/
• GCN Circular #6244
  A. Pelangeon & J-L. Atteia (LATT-OMP) report:
  We have used the spectral parameters of GRB 070402 provided by Golenetskii et al. (GCNC 6243) to compute the spectral pseudo-redshift** of this burst detected by the IPN network (Hurley et al., GCNC 6241, GCNC 6242).
  We find a pseudo-redshift pz= 3.36 +/- 1.00
  ** cf. http://www.ast.obs-mip.fr/grb/pz
• GCN Circular #6246
  E. Sonoda, M. Yamauchi (Univ. of Miyazaki), K. Yamaoka, Y.E. Nakagawa, S. Sugita (Aoyama Gakuin U.), M. Ohno, T. Takahashi, T. Asano, T. Uehara, Y. Fukazawa (Hiroshima U.), Y. Urata, M. Tashiro, K. Abe, K. Onda, Y. Sato, M. Suzuki, N. Kodaka (Saitama U.), T. Enoto, R. Miyawaki, K. Makishima (Univ. of Tokyo), M. Suzuki, T. Tamagawa, Y. Terada (RIKEN), S. Hong (Nihon U.), K. Nakazawa, M. Kokubun, T. Takahashi (ISAS/JAXA), on behalf of the Suzaku WAM team report:
  The IPN-localized long GRB 070402 (Hurley et al., GCN 6241 and 6242) triggered the Suzaku Wide-band All-sky Monitor (WAM), which covers the energy range of 50 keV - 5 MeV, at 15:48:35 UT (=T0). The light curve shows multiple separate pulses with the total duration of about 17 s. The fluence in 100 keV - 3 MeV was 1.09 (-0.15, +0.06) x 10 ^-5 erg/cm2, while the 1-s peak flux measured from T0+5 s was 5.55 (-0.43, +0.30) photons/cm2/s in the same energy range.
  Preliminary result shows that the time-averaged spectrum from T0 to T0+12 s can be described by a power law with an exponential cutoff model as follows:

  dN/dE ~ E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
  alpha = 1.29 (-0.23, +0.21) and
  Epeak = 376 (-46, +74) keV (chi2/d.o.f. = 67/48).
  

  All the quoted errors are at the 90% confidence level, while systematic errors are not included.
  The WAM light curve of this event is available at http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/grb_table.html