{
  "eventType": [
    "GRB",
    "Optical Transient"
  ],
  "body": "N. Klingler (NASA-GSFC / UMBC / CRESST II) and E. Ambrosi (INAF-IASFPA) report on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 260925A 115 s after the BAT trigger (Ambrosi et al., GCN Circ. 45739).  No optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 45746) is detected in the initial UVOT exposures.  Preliminary 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           115          265          147         >20.0\nu_FC               273          523          246         >19.1\nwhite              115         1372          358         >20.9\nv                  603         1249           78         >17.9\nb                  529         1348           62         >18.2\nu                  273         1323          304         >19.3\nw1                 652         1299           55         >18.3\nm2                1079         1099           19         >17.6\nw2                 578          771           39         >18.3\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.039 in the direction of the burst (Schlegel et al. 1998).",
  "subject": "GRB 260925A: Swift/UVOT Upper Limits",
  "createdOn": 1790369309489,
  "submittedHow": "web",
  "eventId": "GRB 260925A",
  "submitter": "noelklin@umbc.edu",
  "format": "text/plain",
  "circularId": 45752
}