{
  "bibcode": "2021GCN.30785....1S",
  "body": "M. H. Siegel (PSU) and E. Sonbas (Adiyaman Univ.)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 210905A\n157 s after the BAT trigger (Sonbas et al., GCN Circ. 30765).\nNo optical afterglow consistent with the XRT position\n(Beardmore et al. GCN Circ. 30768) 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 first\nfinding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nu_FC               157          407          246         >20.1\nv                 4193         4393          197         >19.3\nb                 3782         3982          197         >21.4\nw1                4603         4803          197         >20.1\nm2                4398         4597          197         >19.5\nw2                3988         4188          197         >19.4\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.034 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 30785,
  "createdOn": 1631163593000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 210905A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 210905A"
}