{
  "bibcode": "2015GCN.18150....1M",
  "body": "F. E. Marshall (NASA/GSFC) and V. D'Elia (ASDC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 150817A\n3955 s after the BAT trigger (D'Elia et al., GCN Circ. 18143).\nNo optical afterglow consistent with the enhanced X-ray\nposition (Osborne et al. GCN Circ. 18146) or\nthe optical position (Butler et al. GCN Circ. 18145)\nis 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          3955         4104          147         >20.5\nwhite             3955        12079          930         >21.4\nv                 4111        28678         1278         >20.9\nb                 4932        17880         1723         >21.7\nu                 4727        23627         2613         >21.7\nw1                4522        22957         2144         >21.0\nw2               26865        27765          886         >20.5\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.48 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 18150,
  "createdOn": 1439829291000,
  "email": "femarsha@khamseen.gsfc.nasa.gov",
  "subject": "GRB 150817A: Swift/UVOT Upper Limits",
  "submitter": "Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>",
  "eventId": "GRB 150817A"
}