{
  "bibcode": "2018GCN.22605....1S",
  "body": "M. H. Siegel (PSU) 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 180404A\n90 s after the BAT trigger (Gropp et al., GCN Circ. 22589).\nA source consistent with the XRT position\n(Osborne et al. GCN Circ. 22592)\nis detected in the initial UVOT exposures.\n\nThe preliminary UVOT position is:\n   RA  (J2000) =  05:34:11.64 =  83.54850 (deg.)\n   Dec (J2000) = -37:10:03.9  = -37.16774 (deg.)\nwith an estimated uncertainty of 0.50 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric system\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 (fc)          90          240          147         19.47 +/- 0.09\nwhite               90          770          180         19.34 +/ -0.10\nwhite             45830       52026         1028        >21.66\nv                  632         5179           99        >18.9\nb                  558          750           39        >19.4\nu (fc)              302         552          246         18.95 +/- 0.12\nu                  303          726          265         18.95 +/ -0.14\nw1                 682          701           19        >17.8\nm2                 656          676           19        >17.4\nw2                 607         5094          216         19.45 +/- 0.28\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.04 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 22605,
  "createdOn": 1522947893000,
  "email": "siegel@swift.psu.edu",
  "subject": "GRB 180404A: Swift/UVOT Detection",
  "submitter": "Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>",
  "eventId": "GRB 180404A"
}