TITLE: GCN CIRCULAR NUMBER: 6159 SUBJECT: GRB 070227: TAROT La Silla observatory optical observations DATE: 07/02/28 21:51:23 GMT FROM: Alain Klotz at CESR-CNRS Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report: We imaged the field of GRB 070227 detected by SWIFT (trigger 262347) with the TAROT robotic telescope (D=25cm) located at the European Southern Observatory, La Silla observatory, Chile. The observations started 7.76 hours after the GRB trigger (5.2s after the notice). The elevation of the field decreased from 41 degrees above horizon, weather conditions were excellent and the moon elevation was less than 10 degrees. The date of trigger : t0 = 2007-02-27T22:21:58.752 We co-added a series of 26 long exposures taken between t0+7.76h and t0+8.98h. The co-added image has a limiting magnitude R~20.2. The field is very crowded. We do not detect any OT in the BAT refined error box (Barbier et al. GCNC 6158) nor in the XRT one (Pagani et al. GCNC 6157). Concerning the XRT error box, we detected clearly all stars present in the USNO-B1 catalog or in the DSS-R image. Magnitudes are not corrected for galactic dust extinction. N.B. Galactic coordinates are lon=261.2574 lat= -8.2038 and the galactic extinction in R band is 0.7 magnitudes estimated from D. Schlegel et al. 1998ApJ...500..525S. This message may be cited.