{
  "bibcode": "2021GCN.30975....1K",
  "body": "N. P. M. Kuin (UCL-MSSL) and S. Dichiara (NASA/GSFC/UMCP) report\non behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 211023B\n98 s after the BAT trigger (Dichiara et al., GCN Circ. 30960).\nA source consistent with the XRT position (Beardmore et al. GCN Circ. 30966)\nis detected in the initial UVOT exposures.\n\nThe preliminary UVOT position is:\n    RA  (J2000) =  11:21:14.33 = 170.30971 (deg.)\n    Dec (J2000) = +39:08:08.8  =  39.13579 (deg.)\nwith an estimated uncertainty of 0.53 arc sec. (radius, 90% confidence).\n\nPreliminary detections and 3-sigma upper limits using the UVOT photometric\nsystem\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               98          247          147         19.44 +/- 0.11\nv                  640         1753          136        >18.8\nb                  566         1679          117        >19.9\nu                  310          734          265         19.50 +/- 0.20\nw1                 690         1803          117        >19.3\nw2                 615         1039           39        >19.9\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.024 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 30975,
  "createdOn": 1635099709000,
  "email": "npkuin@gmail.com",
  "subject": "GRB 211023B: Swift/UVOT Detection",
  "submitter": "Paul Kuin at MSSL  <npkuin@gmail.com>",
  "eventId": "GRB 211023B"
}