{
  "bibcode": "2021GCN.29841....1S",
  "body": "M. H. Siegel (PSU) and S. L. Laha (GSFC/UMBC/CRESST)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 210419A\n136 s after the BAT trigger (Laha et al., GCN Circ. 29828).\nNo optical afterglow consistent with the XRT position\n(Osborne et al., GCN Circ 29830)\nis 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           136          286          147         >18.1\nu_FC               294          544          246         >17.9\nwhite              136         1027          333         >18.1\nv                  627         1079           58         >17.5\nb                  550          746           39         >17.7\nu                  294          721          265         >17.9\nw1                 677          871           39         >17.8\nm2                 651         1103           58         >18.3\nw2                 119         1053           67         >19.3\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.075 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 29841,
  "createdOn": 1618933781000,
  "email": "mhs18@psu.edu",
  "subject": "GRB 210419A: Swift/UVOT Upper Limits",
  "submitter": "Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>",
  "eventId": "GRB 210419A"
}