{
  "submittedHow": "web",
  "bibcode": "2025GCN.40011....1S",
  "eventId": "GRB 250329B",
  "createdOn": 1743608399278,
  "format": "text/plain",
  "body": "M.H. Siegel (PSU) and R. Caputo (GSFC) reports on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 250329B 7.4 ks after the SVOM trigger  sb25032902 (Xie et al., GCN Circ. 39925). We do not detect an afterglow at the position of the XRT counterpart (Beardmore et al., GCN Circ. 39939).\n\nPreliminary detections and 3-sigma upper limits for the early exposures are:\n\nFilter\t\tT_start(s)\tT_stop(s)\tExp(s)\t\tMag(AB)\nu                 7392            8531          1121            >21.00\nu                92986          110466          2225            >20.80\n\nThe magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998).",
  "subject": "GRB 250329B: Swift/UVOT Upper Limit",
  "submitter": "Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>",
  "circularId": 40011
}