{
  "bibcode": "2022GCN.31917....1S",
  "body": "M. H. Siegel 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 220412B\n89 s after the BAT trigger (Gropp et al., GCN Circ. 31886).\nNo optical afterglow consistent with the BAT position\n(Sakamoto et al., GCN Circ. 31910) is 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 initial exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite (fc)          89          217          128         >20.0\nwhite             4378         4577          197         >20.3\nb                 4173         4373          197         >19.8\nu                 3968         4167          197         >19.4\nw2                4584         4663           78         >19.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.060 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 31917,
  "createdOn": 1650332467000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 220412B: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 220412B"
}