{
  "bibcode": "2017GCN.21835....1S",
  "body": "M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 170906C\n1296 s after the BAT trigger (Siegel et al., GCN Circ. 21826).\nNo optical afterglow consistent with the XRT position\n(Evans et al. GCN Circ. 21828)\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          1296         1446          147         >21.6\nwhite             1296         2585          284         >21.4\nv                 1578         2635          136         >19.4\nb                 1504         2913          333         >19.9\nu                 1479         2708          156         >20.6\nw1                1454         2684          156         >19.9\nm2                2467         2487           19         >17.8\nw2                2591         2611           19         >19.0\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).",
  "circularId": 21835,
  "createdOn": 1504716616000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 170906C: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 170906C"
}