{
  "bibcode": "2018GCN.22627....1M",
  "body": "F. E. Marshall (NASA/GSFC) and J. D. Gropp (PSU)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 180410A\n179 s after the BAT trigger (Gropp et al., GCN Circ. 22620).\nNo optical afterglow consistent with the enhanced XRT position\n(Evans et al. GCN Circ. 22622)\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           179          329          147         >20.6\nu_FC               338          587          246         >20.0\nwhite              179         2068          450         >20.9\nv                  669         1943          156         >19.2\nb                  594         2043          156         >20.1\nu                  338         2017          382         >20.4\nw1                 718         1993          136         >20.1\nm2                 693         1968          136         >20.3\nw2                 644         2093          175         >19.9\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.92 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 22627,
  "createdOn": 1523384284000,
  "email": "marshall@milkyway.gsfc.nasa.gov",
  "subject": "GRB 180410A: Swift/UVOT Upper Limits",
  "submitter": "Frank Marshall at Swift/UVOT  <marshall@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 180410A"
}