{
  "bibcode": "2005GCN..3227....1H",
  "body": "S. T. Holland (GSFC-USRA), M. Capalbi (ASDC), A. Morgan, S. Kobayashi,\n(PSU), A. Breeveld (MSSL), P. Boyd (GSFC-UMBC), N. Gehrels (GSFC), D.\nHinshaw (GSFC-SPSYS), K. Mason (MSSL), J. Nousek (PSU), and A. Wells\n(Leicester) on behalf of the Swift UVOT team report:\n\n     The Swift Ultra-Violet/Optical Telescope (UVOT) observed the field of\nGRB 050408 (Sakamoto et al., GCN 3189) starting at 17:07:08 UT on 8 April\n2005.  There is a faint source at the location of the optical afterglow\n(de Ugarte Postigo et al., GCN 3192) visible in the coadded U-band image.  \nThis source has U = 21.30 (-0.32,+0.45) mag and the total coadded exposure\ntime is 2927 s.  This source is at the 3-sigma detection limit of the\ncoadded image and is only marginally consistent with being a point source.  \nThere is no detection in the other filters.  The 3-sigma limiting\nmagnitudes in a 3.5 arcsecond radius circular aperture , and the coadded\nexposure times, are: V = 21.3 (3866 s), B = 22.2 (2910 s), UVW1 = 17.8\n(3223 s), UVM2 = 17.6 (1989 s), and UVW2 = 17.82 (3402 s).  The magnitudes\nreported in this Circular are based upon preliminary flight calibrations.\n\n     The first Swift/UVOT image of the field was a 100 s V-band exposure\ncentred 45.117 minutes after the BAT trigger.  No source is detected in\nthis image down to a 3-sigma limiting magnitude of V = 19.9.",
  "circularId": 3227,
  "createdOn": 1113173677000,
  "email": "sholland@milkyway.gsfc.nasa.gov",
  "subject": "GRB 050408: Early Optical/Ultraviolet Observations with Swift/UVOT",
  "submitter": "Stephen Holland at USRA/NASA/GSFC/SSC  <sholland@milkyway.gsfc.nasa.gov>",
  "eventId": "GRB 050408"
}