{
  "bibcode": "2012GCN.13057....1O",
  "body": "S. R. Oates (MSSL-UCL) and M. Stamatikos (OSU/NASA/GSFC)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB 120312A\n105 s after the BAT trigger (Stamatikos et al., GCN Circ. 13049).\nNo optical afterglow consistent with the XRT position \n(Mangano et al., GCN Circ 13053) or the WHT optical candidate \nposition (Tanvir et al., GCN Circ 13055) 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           105          255          147         >21.3\nu_FC               318          567          246         >20.6\nwhite              105         7764          861         >21.9\nv                  647        18848         1378         >20.5\nb                  573         7559          568         >20.9\nu                  318        13854         1583         >21.3\nw1                 696        13039         1434         >21.0\nm2                 844        19630         1998         >21.4\nw2                 795        17934         1434         >21.4\n\nThe magnitudes in the table are not corrected for the Galactic extinction\ndue to the reddening of E(B-V) = 0.071 in the direction of the burst\n(Schlegel et al. 1998).",
  "circularId": 13057,
  "createdOn": 1331637116000,
  "email": "sro@mssl.ucl.ac.uk",
  "subject": "GRB 120312A: Swift/UVOT Upper Limits",
  "submitter": "Samantha Oates at MSSL  <sro@mssl.ucl.ac.uk>",
  "eventId": "GRB 120312A"
}