{
  "bibcode": "2007GCN..7016....1S",
  "body": "P. Schady (MSSL/UCL) and J.L. Racusin (PSU) report on behalf of the Swift \nUVOT team:\n\nThe Swift/UVOT observed the field of GRB 071028 (GCN 7012; Racusin et al.) \nbeginning 128 seconds after the BAT trigger. No afterglow is detected in \nany of the UVOT filters within the XRT error circle (Racusin et al., GCN \n7014). As already noted by Xin et al. (GCN 7015), the refined XRT position \n(Racusin et al., GCN 7014) lies next to a very bright star (V<10 mag), \nseverely limiting the detection of an optical afterglow.\n\nIn the case of the white band and optical filters (v,b,u), contamination \nfrom the nearby, bright star is causing the exposures to be affected by \ncoincidence loss to a degree that is outside the photometrically \ncalibrated range of UVOT. This limits the depth of our observations at the \nXRT position in these filters to white > 13.86, v > 11.46, b > 12.68 and u \n> 11.91.\n\nThe 3-sigma upper limits at the XRT position in co-added UV exposures are as \nfollows:\n\nFilter   Tmid  Exp   Magnitude\n          (s)   (s)   (3-sigma UL)\nuvw1     5044  412    > 19.89\nuvm2     4847  413    > 20.32\nuvw2     5014  213    > 19.67\n\nwhere Tmid is the mid time of the observations. The values quoted above are not \ncorrected for the expected Galactic extinction corresponding to a reddening of \nE_{B-V} = 0.06 mag in the direction of the burst (Schlegel et al. 1998).",
  "circularId": 7016,
  "createdOn": 1193677959000,
  "email": "ps@mssl.ucl.ac.uk",
  "subject": "Swift UVOT upper limits to GRB071028",
  "submitter": "Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>",
  "eventId": "GRB 071028"
}