{
  "bibcode": "2008GCN..8450....1H",
  "body": "S. T. Holland (CRESST/USRA/GSFC) & T. Sakamoto (NASA/UMBC) report on\nbehalf of the Swift/UVOT team:\n\n        The Swift/UVOT observed the field of GRB 081029 starting 2708 s\nafter the BAT trigger (Sakamoto et al., 2008, GCNC 8435).  The late\nstart to the follow-up observations is due to an Earth limb constraint\nat the time of the BAT trigger.  We detect the optical afterglow\n(Rykoff et al., GCNC 8436) in the v, b, and white filters.  This is\nconsistent with a redshift of z = 3.8479 (D'Elia, et al., 2008, GCNC\n8438).  The refined UVOT source position is\n\n   RA (J2000.0) =  23:07:05.35 = 346.77229 (deg)\n  Dec (J2000.0) = -68:09:19.8  = -68.15549 (deg)\n\nwith an estimated uncertainty of 0.5 arcsec (radius, 90% confidence,\nstatistical + systematic).\n\n      Magnitudes and 3-sigma upper limits are reported below.  TSTART\nand TSTOP are the start and stop times of the exposure, in seconds\nsince the BAT trigger.  Exposure is the total exposure time, in\nseconds, during that interval.\n\nFilter   TSTART    TSTOP   Exposure       Mag  Err  Comments\n     v      2687     2887        197     19.02 0.20\n            8557     8757        197     18.66 0.21\n     b      3072     3272        197    >20.5        3-sigma upper limit\n            4507     4707        197     20.05 0.20\n     u      2867   21,932       1601    >21.9        3-sigma upper limit\n   uvw1     4097   21,019       1968    >21.8        3-sigma upper limit\n   uvm2     3892   16,685       1590    >21.7        3-sigma upper limit\n   uvw2     3482   15,250       1279    >21.7        3-sigma upper limit\n  white     2708     7856        147     20.50 0.30\n            4712     4912        197     19.41 0.10\n\nThe above magnitudes are not corrected for the Galactic extinction\ncorresponding to a reddening of E_{B-V} = 0.03 mag (Schlegel et al.,\n1998, ApJS, 500, 525).  The photometry is on the UVOT photometric\nsystem described in Poole et al. (2008, MNRAS, 383,627).  The\npower-law decay index in the v band between 8557 and 15,864 s is\nconsistent with no decay.",
  "circularId": 8450,
  "createdOn": 1225298461000,
  "email": "sholland@milkyway.gsfc.nasa.gov",
  "subject": "GRB 081029: UVOT Detection of the Optical Afterglow",
  "submitter": "Stephen Holland at USRA/NASA/GSFC/SSC  <sholland@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 081029"
}