{
  "subject": "GRB 170728B: Swift/UVOT Further Analysis",
  "eventId": "GRB 170728B",
  "bibcode": "2017GCN.21399....1L",
  "createdOn": 1501529510000,
  "circularId": 21399,
  "submitter": "Sam LaPorte at PSU  <sjl5346@psu.edu>",
  "email": "sjl5346@psu.edu",
  "body": "GRB 170728B: Swift/UVOT Detection\n\nS. J. LaPorte (PSU), S.W.K. Emery (MSSL), and S. B. Cenko (GSFC)\nreport on behalf of the Swift/UVOT team:\n\nAfter detailed analysis of initial data reported in LaPorte and Cenko, \nGCN Circ. 21388, we do find a significant detection in initial optical \nfilter exposures.\n\nThe Swift/UVOT began settled observations of the field of GRB 170728B\n473 s after the BAT trigger (Cenko et al., GCN Circ. 21371).\nA fading source consistent with the optical position\n(D'Avanzo et al. GCN Circ. 21373)\nis detected in the initial UVOT exposures.\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric\nsystem\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: \n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite              876         1026          147         20.56 +/- 0.20\nv                  630         8278          627         20.23 +/- 0.27\nb                  728         2561          194         20.60 +/- 0.29\nu                  703        13868         1276        >21.2\nw1                 679        19251         2000        >21.6\nm2                6847        18681         1279        >22.1\nw2                6437         8073          393        >21.5\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.03 in the direction of the burst\n(Schlegel et al. 1998)."
}