{
  "bibcode": "2018GCN.23277....1S",
  "body": "M. H. Siegel (PSU) and T. N. Ukwatta (LANL)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 180924A\n83 s after the BAT trigger (Ukwatta et al., GCN Circ. 23261).\nNo optical afterglow consistent with the XRT position\n(Evans et al. GCN Circ. 23262)\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            83          233          147         >20.8\nu_FC               241          491          246         >19.7\nwhite               83          542          167         >20.9\nv                  572          592           19         >17.1\nb                  497          517           19         >18.4\nu                  241          491          246         >19.7\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": 23277,
  "createdOn": 1538108210000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 180924A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 180924A"
}