{
  "bibcode": "2015GCN.17938....1G",
  "body": "S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,\nM. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline\non behalf of the Konus-Wind team, report:\n\nOn June 15, 2015 Konus-Wind detected a hard X-ray transient\nactivity lasting from ~65300 s UT (18:08:20) to\n~69000 s UT (19:10:00).\nTaking into account the proximity of this burst\nto the Swift/BAT trigger due to V404 Cygni\n(T0=T0(BAT)=18:31:38 UT; Barthelmy et al., GCN 17929),\ntwo subsequent Fermi/GBM triggers due to\nthe same source (Younes, GCN 17932), and\nconsistency of the KW ecliptic latitude response with\nthe position of V404 Cygni we suggest that KW observed\nthe ~1 hour-long flare from this Galactic black hole candidate.\n\nThe KW light curve recorded in the waiting mode shows\na multi-peaked complex which started at ~T0(BAT)-1400 s,\npeaked at ~T0(BAT)+1640 s, and lasted until ~T0+2300 s.\nThe emission is visible in the instrument's\nG1 (20-75 keV) and G2 (75-300 keV) bands.\n\nThe K-W light curve is available at\nhttp://www.ioffe.rssi.ru/LEA/V404_Cyg/KW150615_V404_Cyg/\n\nAs observed by Konus-Wind, the burst had a fluence of\n(1.8 �� 0.1)x10^-4 erg/cm2, and a 2.944-s peak flux,\nmeasured from ~T0+1642 s, of (2.3 �� 0.4)x10^-7 erg/cm2/s\n(both in the 20 - 1200 keV energy range).\n\nModeling the 3-channel time-integrated spectrum\n(from T0-1394.283 s to T0+2315.157 s) by a power law\nwith exponential cutoff (CPL) model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nyields alpha = -1.28 �� 0.16, and Ep = 122 �� 9 keV.\n\nAssuming the distance 2.4 kpc (Miller-Jones et al. 2009)\nthe energy release in the flare is E ~ 8.9x10^40 erg,\nand the peak luminosity L is ~1.1x10^38 erg/s.\n\nFurther KW observations of the activity of the source will\nbe reported (there are at lest two episodes detected\nby the instrument on June 16, 2015).\n\nAll the quoted errors are estimated at the 1 sigma confidence level.\nAll the presented results are preliminary.",
  "circularId": 17938,
  "createdOn": 1434537637000,
  "email": "fred@mail.ioffe.ru",
  "subject": "Konus-Wind observation of Galactic transient V404 Cyg in outburst",
  "submitter": "Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>"
}