{
  "bibcode": "2010GCN.11371....1D",
  "body": "M. De Pasquale, C. Saxton  and S. Oates (UCL-MSSL)\nreport on behalf of the Swift/UVOT team:\n\nThe Swift/UVOT began settled observations of the field of GRB\n101023A 93 s after the BAT trigger (Saxton et al, GCN Circ. 11363)\nwith a 100s finding chart in the white filter.\nUVOT detected a fading optical source, with a position consistent\nwith the enhanced XRT position (Osborne et al, GCN Circ. 11365), in\nthe white filter exposures and, very marginally, in the first u\nband exposure. We identify this object as the optical afterglow\nof GRB101023A.\nThere is no detection of this source in other filters, either in\nsingle or summed up exposures.\n\nThe position of this optical afterglow is\n\nRA =21h 11m 51.26s (317.96360)\nDec = -65d 23m 15.7s (-65.38769) (J2000)\n\nwith an estimated uncertainty of 0.6 arcsec. This position is\nconsistent with the source identified by Gemini (Levan et al,\nGCN Circ. 11366) and GROND Nardini et al., GCN 11369). We caution\nthat the photometry of this object is rather complicated by the\npresence of a bright star 13rd magnitude star, which is located\nabout 15 arcseconds from the optical afterglow.\n\nPreliminary magnitudes and 3-sigma upper limits using the UVOT\nphotometric system (Poole et al, 2008, MNRAS, 383, 627) for the\ninitial exposures are:\n\nFilter      T_start(s)  T_stop(s)   Exp(s)        Mag\n\nwhite (fc)      93        193        100     19.4 +/- 0.2\nwhite         5895      10094        960     21.7 +/- 0.4 (2.8 sigma)\nv             3524      15873       1082         >20.2\nb             4344       4483        137         >20.2\nu             4139       4339        200     20.5 +/- 0.6 (2 sigma)\nu            21640      22548        882         >21.1\nw1            3934      21633       1126         >21.1\nm2            3728      16778       1082         >21.2\nw2           10101      10653        544         >21.0\n\n\nThe values quoted above 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": 11371,
  "createdOn": 1287927840000,
  "email": "mdp@mssl.ucl.ac.uk",
  "subject": "Swift/UVOT observations of GRB101023A",
  "submitter": "Massimiliano de Pasquale at MSSL-UCL  <mdp@mssl.ucl.ac.uk>",
  "eventId": "GRB 101023A"
}