{
  "bibcode": "2009GCN..9969....1C",
  "body": "P.A. Curran (MSSL-UCL), F. Marshall (GSFC), S. Holland (GSFC) and C.\nPagani (PSU) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 090929B 94s \nafter the BAT trigger (Pagani et al., GCN Circ. 9963). No optical \nafterglow is detected in the b, u or uvw2 UVOT exposures. There is a \ndetection in the white filter, consistent with the enhanced XRT position \n(Goad et al. GCN 9964, Page et al. GCN 9965), the proposed optical \ncounterpart (Wren et al. GCN 9967) and a USNO catalogued star (R2=19.3). \nSince the photometry is contaminated by a bright (R = 9.5), near-by star, \nwe cannot determine the nature of the source at this time.\n\n\nPreliminary magnitudes and 3-sigma upper limits using the UVOT photometric \nsystem (Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are:\n\nFilter       T_start(s)   T_stop(s)     Exp(s)      Mag\n----------------------------------------------------------------\nwhite        94           4032          292         18.7 +/- 0.5\nb            3627         3827          197         >20.5\nu            3422         3622          197         >20.3\nuvw2         4038         4224          183         >20.3\n\nThe values quoted above are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.07 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 9969,
  "createdOn": 1254251637000,
  "email": "pac@mssl.ucl.ac.uk",
  "subject": "GRB 090929B: Swift/UVOT Observations",
  "submitter": "Peter Curran at MSSL  <pac@mssl.ucl.ac.uk>",
  "eventId": "GRB 090929B"
}