{
  "bibcode": "2009GCN.10289....1D",
  "body": "M. De Pasquale (MSSL/UCL) and H. Krimm (CRESST/GSFC/USRA)\nreport on behalf of the Swift/UVOT team:\n\n  The Swift/UVOT began settled observations of the field of GRB091221\n80s after the BAT trigger with a 150s finding chart exposure in\nthe White filter.\n\n  We detect the optical afterglow in the finding chart exposure.\nThe refined UVOT position is RA = 55.79750, Dec = 23.24119 (J2000), \ncorresponding to\n\n             RA = 03h 43m 11.40s,\n             Dec = +23d 14m 28.3s (J2000)\n\nwith an estimated uncertainty of 0.6 arcsec (radius, 90% confidence).\nThis position is consistent with the XRT enhanced position (Evans\net al., GCN 10287) and ground-based detections (Zheng et al., GCN\n10284; Klose et al., GCN 10286).\n\n  The afterglow is not detected anymore in single or summed exposures\nin all filters. Preliminary magnitudes and 3 sigma upper limits\nare reported below.\n\nFilter    T_start(s) T_stop(s)  Exposure(s)    Mag  Err\n-----------------------------------------------------------------------\nwhite        80        230       149.8       20.19 +/- 0.27\nwhite      3657      11605       927.1          >21.62\nv          4068       5704       393.2          >19.56\nb          3452      11054      1278.4          >21.11\nu          4683      10142      1083.4          >20.68\nuvw1       4478       6075       354.4          >19.96\nuvm2       4273       5909       393.3          >19.79\nuvw2       3863       5499       393.3          >20.07\n------------------------------------------------------------------------\n\nThe values quoted above are not corrected for the heavy Galactic \nextinction corresponding to the reddening of E(B-V) = 0.22 in the \ndirection of the burst (Schlegel et al. 1998, ApJS, 500, 525). The \nphotometry is on the UVOT photometric system described in Poole et al. \n(2008, MNRAS, 383, 627).\n\n[GCN OPS NOTE(22dec09): Per author's request, the Subject-line\nwas changed from 091208B to 091221.]",
  "circularId": 10289,
  "createdOn": 1261490332000,
  "email": "mdp@mssl.ucl.ac.uk",
  "subject": "GRB 091221: Swift/UVOT refined analysis",
  "submitter": "Massimiliano de Pasquale at MSSL-UCL  <mdp@mssl.ucl.ac.uk>",
  "eventId": "GRB 091221"
}