{
  "bibcode": "2017GCN.21984....1M",
  "body": "F. E. Marshall (NASA/GSFC) and J. K. Cannizzo (NASA/UMBC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 171007A\n77 s after the BAT trigger (Cannizzo et al., GCN Circ. 21976).\nNo optical afterglow consistent with the enhanced XRT position\n(Beardmore et al. GCN Circ. 21979)\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            77          227          147         >20.7\nu_FC               291          540          246         >20.4\nwhite               77         6966          805         >21.7\nv                  620         7377          529         >19.5\nb                  546         6761          510         >20.8\nu                  291         6556          559         >20.7\nw1                 669         6351          333         >20.3\nm2                 644         7572          480         >19.9\nw2                 596         7172          529         >20.9\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.02 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 21984,
  "createdOn": 1507653751000,
  "email": "femarsha@khamseen.gsfc.nasa.gov",
  "subject": "GRB 171007A: Swift/UVOT Upper Limits",
  "submitter": "Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>",
  "eventId": "GRB 171007A"
}