{
  "eventId": "GRB 230911C",
  "submitter": "Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>",
  "submittedHow": "email",
  "createdOn": 1694465341825,
  "subject": "GRB 230911C: Swift/UVOT Upper Limits",
  "bibcode": "2023GCN.34665....1B",
  "circularId": 34665,
  "body": "A. A. Breeveld (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 230911C 122 s after the BAT trigger (Sonbas et al., GCN Circ. 34655).\nNo optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 34658) is detected in the initial UVOT exposures.\nPreliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC           122          272          147         >20.4\nwhite              122         4926          289         >21.0\nu_FC               280          530          246         >19.7\nu                  280         4572          708         >20.2\nb                  537         4778          235         >19.8\nw1                 661         4368          216         >19.0\nw2                 587          781           39         >18.2\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.101 in the direction of the burst (Schlegel et al. 1998).\n"
}