{
  "bibcode": "2018GCN.23215....1S",
  "body": "M. H. Siegel (PSU) and V. D'Elia (SSDC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 180905A\n154 s after the BAT trigger (D'Elia et al., GCN Circ. 23201).\nNo optical afterglow consistent with the XRT position\n(D'Elia et al. GCN Circ. 23201) is detected in the initial UVOT exposures,\nas confirmed by Bootes (Hu et al., GCN Circ. 23208), MITSUME (Niwano\net al., GCN Circ. 23211) and RATIR (Watson et al., GCN Circ. 23212).\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           154          289          133         >20.4\nwhite              154         6385          373         >21.1\nv                 5316         5515          197         >19.1\nb                 4700         6335          393         >20.5\nu                 4495         6130          393         >20.3\nw1                5726         5925          197         >19.6\nm2                5520         5720          197         >19.8\nw2                5111         5311          197         >19.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.60 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 23215,
  "createdOn": 1536521858000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 180905A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 180905A"
}