{
  "bibcode": "2006GCN..4988....1L",
  "body": "V. Lipunov, V.Kornilov, N.Tyurina, A.Belinski, D.Kuvshinov, E.Gorbovskoy,\nA.Krylov, G.Borisov, A.Sankovich,  V.Vladimirov, P.Gritsyk, S.Korobkin\n\nSternberg Astronomical Institute, Moscow Union 'Optic'\nMASTER  robotic system (http://observ.pereplet.ru) responded\nto GRB060421 (GRB_TIME is 2006-04-21 00:39:23.33, M. R. Goad et al. \nGCN4985).\n\nUnfortunaly 2 minutes before notice time roof closed roboticaly due to \nmeteo alert \"cloudy\". The first image was at 2006-04-21 00:48:45 UT,\n562 s  after the GRB time.\nThe unfiltered image is calibrated relative to USNO A2.0 (0.8 R + 0.2 B).\nThe robot not find OT-candidate in error box brighter then  16.8 (s/n=3) \nat Swift XRT position (Mike Goad, Kim Page GCN4987).\nThis work is supported by RFFI  04-02-16411 grant.\nThis message can be cited.\nMailto: lipunov@sai.msu.ru",
  "circularId": 4988,
  "createdOn": 1145620219000,
  "email": "gcncirc@observ.inetcomm.ru",
  "subject": "GRB(?)060421:MASTER optical limit",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <gcncirc@observ.inetcomm.ru>"
}