{
  "bibcode": "2007GCN..6154....1T",
  "body": "Christina C. Thoene (Dark/NBI), D. Alexander Kann (TLS Tautenburg), Thomas                                                    \nAugusteijn (NOT) and Celine Reyle-Laffont (Observatoire de Besancon) \nreport:\n\nWe observed the OT candidate (Thoene et al., GCN 6142) of GRB 070224 \n(Racusin et al., GCN 6137) again on Feb. 27 (2.27 days after the burst) \nwith NOT and StanCam in R.\n\nThe proposed candidate (Thoene et al., GCN 6142, see also Chen et al., GCN\n6145, Mirabal et al., GCN 6146, Rol et al., GCN 6147 and Chen et al., GCN \n6148) is clearly fading between our three epochs.                               \n\nWe get the following magnitudes:\n\nt after burst�� exptime�� R mag:\n0.20 d����������� 900s��������22.1 +- 0.2 \n0.39 d����������� 1800s������ 22.5 +- 0.2\n2.27 d����������� 2400s������ 24.1 +- 0.3\n\nbased on two nearby USNO-B1.0 stars.\n\nWe therefore conclude that this object is the afterglow of GRB 070224.\nIt thus may have had an early plateau phase (Rol et al., GCN 6147, Chen et \nal., GCN 6148).\n\nImproved astrometry gives a refined position of the afterglow at (J2000):\n\nRA = 11:56:06.65  \nDec = -13:19:48.8  \n \nwith an error of 0.5 arcsec. \n\nThis is 1.1 arcsec from the center of the revised XRT error circle \n(Racusin et al., GCN Report 36.1) and 0.8 arcsec from the center of Nat \nButler's error circle (v2.5) \n(http://astro.berkeley.edu/~nat/swift/xrt_pos.html).",
  "circularId": 6154,
  "createdOn": 1172603524000,
  "email": "kann@tls-tautenburg.de",
  "subject": "GRB 070224: Optical afterglow confirmation",
  "submitter": "Alexander Kann at TLS Tautenburg  <kann@tls-tautenburg.de>",
  "eventId": "GRB 070224"
}