TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5147 SUBJECT: GRB 060210: Jet Break in the XRT light curve DATE: 06/05/18 00:59:16 GMT FROM: Xinyu Dai at Ohio State U X. Dai and K. Z. Stanek (Ohio State Univ.) We analyzed the Swift-XRT light curve of GRB 060210 (Beardmore et al. 2006 GCN 4724). We added new data points to the X-ray light curve presented in Stanek et al. 2006 (astro-ph/0602495 v1) up to 1.e6 sec after the BAT trigger. We detected a smooth jet break (t_j = 7.9^{+2.2}_{-1.6} hr, observed) with the extended XRT light curve. We fitted both a single power-law and a broken power-law model to the XRT light curve from 3.e3 sec to 1.e6 sec after the BAT trigger. For the single power-law model we found alpha=1.09 and chi^2(dof) = 292.3(69). For the broken power-law model we found alpha1 = 0.7, alpha2 = 1.4, t_j = 7.9 hr, and chi^2(dof) = 64.8(67). We note that the power-law decay index for the X-ray light curve before the jet break (alpha1 ~ 0.7) is not consistent with the optical index (alpha_o ~ 1.3, Stanek et al. 2006 astro-ph/0602495). The XRT light curve for GRB 060210 is at http://www.astronomy.ohio-state.edu/~xinyu/grb/060210.jpg This message may be cited.