{
  "bibcode": "2015GCN.18462....1S",
  "body": "M. H. Siegel (PSU), B. G. Balzer (PSU) and P. D'Avanzo (INAF-OAB)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 151023A\n796 s after the BAT trigger (D'Avanzo et al., GCN Circ. 18450).\nNo optical afterglow consistent with the XRT position\n(D'Avanzo et al. GCN Circ. 18450) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC           796          946          147         >19.6\nwhite              796         2140          411         >20.0\nv                 1130         2191          136         >18.5\nb                 1229         2116          117         >19.3\nw1                1354         1374           19         >18.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 1.42 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 18462,
  "createdOn": 1445652935000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 151023A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 151023A"
}