{
  "bibcode": "2021GCN.30857....1S",
  "body": "M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 210919A\n100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 30846).\nNo optical afterglow consistent with the XRT position\n(Goad et al. GCN Circ. 30850) 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\nwhite_FC           100          249          147         >20.8\nu_FC               312          561          246         >19.9\nwhite              100         1193          343         >21.4\nv                  643         1244           70         >18.7\nb                  568         1342           63         >19.3\nu                  312         1318          304         >19.8\nw1                 693         1293           58         >19.7\nm2                1248         1268           19         >19.0\nw2                 618         1044           39         >19.4\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.141 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 30857,
  "createdOn": 1632191714000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 210919A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 210919A"
}