{
  "bibcode": "2009GCN..9252....1G",
  "body": "E. Gorbovskoy, V. Lipunov, V.Kornilov, A.Belinski, N.Shatskiy, N.Tyurina,\nD.Kuvshinov, P.Balanutsa, V.V.Chazov, P.V.Kortunov, A.Kuznetsov\nSternberg Astronomical Institute, Moscow State University\n\nK.Ivanov, S.Yazev\nIrkutsk State University\n\nA. Tlatov, A.V. Parhomenko,\nKislovodsk Solar Station of the Pulkovo Observatory\n\nV.Krushinski, I.Zalognikh, T.Kopytova\nUral State University, Kourovka\n\n\nThere are 6 MASTER Very Wide Field cameras located at Kislovodsk and Irkutsk \nwith common FOW = 6000 square degrees (http://observ.pereplet.ru/).\n\nOne of the two  MASTER Very Wide Field Cameras located at Irkutsk\n(D=50 mm, 2x1000 square degrees, 11 Mpx, 72\" per pix in binning regime) has \nobserved  UVOT error box (Cannizzo et al., GCN 9223) with 1s exposure befoure, \nduring and after GRB Time without time gap between images.\nThe error box is near at the center of our FOW.\n\nOur unfiltered images are calibrated relative to Tycho stars (V) and very \nclose to V band.\nThe magnitude limit of the each emage is  ~8 m at the center of FOW (some \ncloudy on the sky). The limit of coadded six images ~ 9 m.\n\nWe do not detect OT.\n\nOur observations results:\n\n----------------------------------------------------------------------\nFermi GRB Trigg.*     Exposure   Mag Limit   Optical Flux        Coadd?\ntime (sec)            (sec)        (m)       (erg/sm^2 s)\n----------------------------------------------------------------------\n     -2                  1          8.1        1.3x10^-8            No\n     -1                  1          8.1        1.3x10^-8            No\n      0                  1          8.0        1.4x10^-8            No\n     +1                  1          8.0        1.4x10^-8            No\n     +2                  1          8.0        1.4x10^-8            No\n     +3                  1          7.9        1.5x10^-8            No\n     +4                  1          8.0        1.4x10^-8            No\n     +5                  1          8.0        1.4x10^-8            No\n  -60 : +120             1          ~8        ~1.4x10^-8            No\n     -6                  6          8.9        7.0x10^-9            Yes\n     +0                  6          8.7        7.3x10^-9            Yes\n     +6                  6          8.8        7.2x10^-9            Yes\n    +12                  6          8.9        7.0x10^-9            Yes\n    -60                 60          9.7        3.0x10^-9            Yes\n      0                 60          9.7        3.0x10^-9            Yes\n     60                 60          9.5        3.5x10^-9            Yes\n-----------------------------------------------------------------------\n*Fermi GBM Trigger Time = 14:12:08.67 (Connaughton, GCN 9230)  1% \ncoincident with our start zero image time.\n\n1). the optical fluence during  GRBurst is limited by\n\n  0 up to +6 s                       ~<=  1 x 10E-7 erg/cm^2\n  0 up to +60 s                       <=  5 x 10E-7 erg/cm^2\n\nincluding  total absorbtion 1 magnitude in V band.\n(The absorption column density NH = (0.20 +/-  0.01) x10^22 cm^-2\nfrom Swift XRT spectrum data, Margutti, GCN 9237).\n\nThe event fluence (8-1000 keV) in this time interval is\n(5.2 +/- 0.1)E-05 erg/cm^2 (Connaughton, GCN 9230).\n\nSo:\n\n2).\n\nOptical-Fluence(6s)/Gamma-Fluence (8-1000 keV)  ~ < 1/500\nOptical-Fluence(60s)/Gamma-Fluence(8-1000 keV)  ~ < 1/100\n\nThe same ratio for  GRB080319B is\n\nOptical-Fluence/Gamma-Fluence(8 - 1000 keV) ~ 1/140\n\n(Naked Eye GRB, Racusin, Karpov et al., Nature, vol.455, 183, 2008).\n\n\nThe light curve and film  of our observations  is available at\n\nhttp://observ.pereplet.ru/images/GRB090424/GRB090424.html\n\n\nThe reduction is continued.\n\nThe message may be cited.\n\nmailto: lipunov@sai.msu.ru",
  "circularId": 9252,
  "createdOn": 1240691382000,
  "email": "gcncirc@observ.inetcomm.ru",
  "subject": "GRB 090424: MASTER-Net prompt optical limit",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>",
  "eventId": "GRB 090424"
}