{
  "bibcode": "2007GCN..6745....1G",
  "body": "S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, and\nT. Cline on behalf of the Konus-Wind team,\n\nK. Yamaoka, M. Ohno, C. Kira, Y. Fukazawa, T. Takahashi, M. Tashiro,\nY. Terada, T. Murakami, and K. Makishima\non behalf of the Suzaku WAM team, report:\n\nAt 2007-08-07 ~23:40 UT, Konus-Wind detected the onset of a very long \nsoft event which had been observed at least until 2007-08-08 ~7:00 UT in \nthe G1 (19-70 keV) and G2 (70-300 keV) bands. The Konus-Wind light curve \nshows multipeaked structure with the maximum intensity at 2007-08-08 \n00:16 UT.\nThe Konus-Wind ecliptic latitude response is consistent with the\nposition of Cyg X-1.\nAt the time, Suzaku-WAM detected emission with the patterns similar to \nthose observed  by the Konus-Wind and occultation steps which correspond \nto the set/rise times of Cyg X-1.\nThe WAM angular response is consistent with the Cyg X-1 position.\nThere is also a flaring seen in the XTE-ASM light curve of Cyg X-1 at \nthis time\n(http://heasarc.gsfc.nasa.gov/cgi-bin/xte_weather/xte_lc?source=CYGX1&action=plot)\nThus, we believe this event is a giant outburst from Cyg X-1.\n\nPreliminary analysis of the Konus-Wind data\nshows that the outburst had a fluence of ~1.4x10^-3 erg/cm2\n(in the 15-350 keV) range, the time-integrated spectrum\n(accumulated from 2007-08-07 23:40 to 2007-08-08 07:00 UT)\ncan be described by a power law with exponential cutoff model:\ndN/dE ~ E^(-alpha)*exp(-E*(2-alpha)/Ep)\nwith alpha ~1.0 and Ep ~63 keV.\nThis is the most powerful gamma-ray outburst from Cyg X-1 ever observed.\nThe most powerful Cyg X-1 outburst detected before (on 2002 Feb. 24)\nhad a fluence of 8.0x10^-4 erg/cm2 in the same energy range\n(Golenetskii et al., 2003, ApJ, 596, 1113).\n\nThe Konus-Wind light curve of this outburst is available\nat http://www.ioffe.rssi.ru/LEA/CygX1/070807/",
  "circularId": 6745,
  "createdOn": 1186765291000,
  "email": "val@mail.ioffe.ru",
  "subject": "A giant outburst from Cygnus X-1 detected by Konus-Wind and Suzaku-WAM",
  "submitter": "Valentin Pal'shin at Ioffe Inst  <val@mail.ioffe.ru>"
}