{
  "bibcode": "2005GCN..3699....1W",
  "body": "K. Wiersema (U. of Amsterdam), E. Rol (U. of Leicester),\nR. Starling (U. of Amsterdam), N. Tanvir (U. of Hertfordshire),\nD. S. Bloomfield, H. Thompson (Queen's University Belfast)\n\nreport:\n\nWe have observed the position of the short burst\nGRB 050724 (Covino et al. GCN 3665) with the William Herschel\nTelescope at the Observatorio del Roque de los Muchachos on\nLa Palma, using the Aux port Imager.\n\nWe observed two epochs, with midpoints 0.424 days and 3.405\nafter burst. The epoch 1 observations consisted of\n4 x 15 + 5 minutes exposure time in R band. Epoch 2\nconsisted of 4 x 15 minutes in R band.\nAt the first epoch the weather conditions were good with an\naverage seeing of 0.8 arcsec. During the second epoch the seeing\nwas considerably worse, with an average seeing ~1.3 arcsec.\nPSF-matched image subtraction of the two epochs using the\nISIS code (Alard et al. 1999) reveals a clearly fading source.\nThis behaviour is confirmed in a subtraction of the first and\nlast image from the first epoch. The position of the fading\nsource matches that described in e.g. GCNs 3690 and 3694,\nas well as the radio (GCN 3684) and X-ray afterglow position\n(GCN 3683, 3697).\n\nWe performed aperture photometry of the host galaxy plus the OT\nwith respect to two unsaturated USNO stars: 0624-0502999 and\n0624-0503050, whose values we take from the USNO-B catalogue.\nWe find a magnitude difference of approximately 0.2 magnitudes\nbetween the two epochs.\nAssuming the contribution of the afterglow to the total flux\nat the second epoch to be negligible, we estimate the afterglow to\nbe approximately R ~22.1 at our first epoch.\n\nA jpg image showing the position of the afterglow and the host\ncan be found on:\nhttp://remote.science.uva.nl/~kwrsema/grb050724/\n\nWe thank the staff of the WHT for outstanding support for these\nobservations.",
  "circularId": 3699,
  "createdOn": 1122659890000,
  "email": "kwrsema@science.uva.nl",
  "subject": "GRB 050724: WHT optical observations",
  "submitter": "Klaas Wiersema at GRACE/U of Amsterdam  <kwrsema@science.uva.nl>",
  "eventId": "GRB 050724"
}