  An overdoped YBa2Cu3O7 single crystal was studied by SQUID and torque
magnetometry in order to investigate the temperature dependence of the
anisotropy parameter close to the transition temperature T_c (0.87 T_c < T <
T_c). Angle dependent torque measurements were performed and analyzed with the
widely used Kogan model [Phys. Rev. B 38, 7049 (1988)] as well as with an
extended model by Hao and Clem [Phys. Rev. Lett. 67, 2371 (1991)], taking into
account the influence of the vortex cores on the magnetization. Both approaches
yield similar results, with an out-of-plane anisotropy parameter around 6.5
which slightly increases with decreasing temperature, and a temperature
independent in-plane anisotropy parameter gamma_ab}= 1.12(5).
