{
  "bibcode": "2015GCN.17739....1M",
  "body": "F.E. Marshall (NASA/GSFC) and C. Pagani (U. Leicester)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 150423A\n74 s after the BAT trigger (Pagani et al., GCN Circ. 17728).\nNo optical afterglow consistent with the optical position\n(Source 1 in Varela et al. GCN Circ. 17732; Perley GCN Circ. 17733) \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) exposures and subsequent exposures are:\n\nFilter         T_start(s)   T_stop(s)      Exp(s)         Mag\n\nwhite_FC            74          223          147         >20.8\nu_FC               286          535          246         >20.2\nwhite               74         6067          733         >21.5\nv                  615         6477          452         >20.9\nb                  541         5862          255         >20.9\nu                  286         6924          513         >20.8\nw1                 665         6887          452         >20.9\nm2                5048         6682          393         >20.8\nw2                 591         6273          432         >21.6\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.03 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 17739,
  "createdOn": 1429822800000,
  "email": "femarsha@khamseen.gsfc.nasa.gov",
  "subject": "GRB 150423A: Swift/UVOT Upper Limits",
  "submitter": "Frank Marshall at GSFC  <femarsha@khamseen.gsfc.nasa.gov>",
  "eventId": "GRB 150423A"
}