{
  "bibcode": "2010GCN.11062....1H",
  "body": "S. T. Holland (CRESST/GSFC/USRA) and E. A. Hoversten (PSU)\nreport on the behalf of the Swift UVOT team:\n\n      The Swift/UVOT observed the field of GRB 100805A starting 112 s\nafter the BAT trigger (Hoversten, et al., 2010, GCN Circ. 11047).\nSettled observations started at 130 s.  We detect the optical\nafterglow (Hoversten, et al., 2010, GCN Circ, 11047) in all filters\nexcept uvw2.  The refined UVOT position is\n\n     RA (J2000) =  19:59:30.51  =  299.87713 (deg)\n    Dec (J2000) = +52:37:40.1   =  +52.62783 (deg)\n\nwith an estimated uncertainty of 0.43 arcsec (radius, 90% confidence,\nstatistical + systematic).  This is 1.31 arcsec west of the\nUVOT-enhanced XRT position (Goad, et al., 2010, GCN Circ. 11053).\n\n     Preliminary magnitudes, and 3-sigma upper limits for detecting a\nsource in the finding charts and in the co-added images, are\n\nFilter      T_start   T_stop    Exp(s)      Mag   Err\n-----------------------------------------------------------\nwhite (fc)      130      280       147     18.10 0.08\n    u (fc)      288      538       246     18.32 0.11\n\n    v           619     5984       432     19.80 0.23\n    b           544   10,831      1213     21.22 0.20\n    u           288     6600       659     18.55 0.09\n uvw1           668     6395       432     20.78 0.39\n uvm2           643     6189       432     20.68 0.45\n uvw2           594   12,479      1149    >21.6  3-sigma UL\nwhite           130   11,744      1319     19.42 0.07\n-----------------------------------------------------------\n\n     The quoted magnitudes and upper limits have not been corrected\nfor the expected Galactic extinction along the line of sight\ncorresponding to a reddening of E_{B-V} = 0.19 mag (Schlegel, et al.,\n1998, ApJS, 500, 525).  All photometry is on the UVOT photometry\nsystem described in Poole et al. (2008, MNRAS, 383, 627).\n\n     The non-detection in the UVOT uvw2 filter, and the observed UVOT\nspectral energy distribution at 4895 s, is consistent with GRB 100805A\nhaving a redshift of approximately z = 1.3, although we can not rule\nout the non-detection in uvw2 being due to extinction in the host\ngalaxy.  The white light curve exhibits a power-law decay with an\nindex of alpha = -0.71 +/- 0.03, consistent with what was observed by\nCenko, et al. (2010, GCN Circ. 11051).",
  "circularId": 11062,
  "createdOn": 1281034950000,
  "email": "Stephen.T.Holland@nasa.gov",
  "subject": "GRB 100805A: Swift/UVOT Observations of the Optical Afterglow",
  "submitter": "Stephen Holland at USRA/NASA/GSFC/SSC  <Stephen.T.Holland@nasa.gov>",
  "eventId": "GRB 100805A"
}