{
  "bibcode": "2019GCN.26574....1K",
  "body": "N. P. M. Kuin (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 191221B\n92 s after the BAT trigger (Laha et al., GCN Circ. 26534).\nA source consistent with the XRT position (Beardmore et al. GCN Circ. 26540)\nand ALMA position (Laskar et al., GCN Circ. 26564)  was detected in the\ninitial UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  10:19:19.24 = 154.83017 (deg.)\n    Dec (J2000) = -38:09:27.64 = -38.15768 (deg.)\nwith an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).\n\nPreliminary detections using the UVOT photometric system\n(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures\nare:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)           Mag\n\nwhite               92          241          147         see below\nu                  304          554          246         12.30 +/- 0.02\nb                  560          579           20         13.54 +/- 0.04\nuvw2               610          630           20         13.20 +/- 0.06\nv                  635          655           20         13.42 +/- 0.05\nuvm2               659          679           20         12.79 +/- 0.06\nuvw1               684          704           20         12.82 +/- 0.05\n\nAperture photometry shows initially a completely saturated detector,\nleading\nto wh < 13.8 mag. The first exposure in the white filter (tstart=T0+92s)\nshows a readout streak but the readout streak traverses also another\nrelatively bright star which leads to a saturated readout streak\nand precludes using that method of determining the magnitude (Page\net al, 2013 MNRAS 436, 1684).   Analysis continues.\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.08 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 26574,
  "createdOn": 1577189319000,
  "email": "npkuin@gmail.com",
  "subject": "GRB 191221B: Swift/UVOT Detection",
  "submitter": "Paul Kuin at MSSL  <npkuin@gmail.com>",
  "eventId": "GRB 191221B"
}