Spectroscopy and photometry of AP And

We have obtained very extensive measurements of the light curve (19097 differential V magnitude observations) and a radial velocity curve (83 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.277+/-0.004 and 1.251+/-0.004M_{sun}_, radii of 1.233+/-0.006 and 1.1953+/-0.005R_{sun}_, and temperatures of 6565+/-150K and 6495+/-150K.

The distance to the system is about 400+/-30pc. Comparison with the theoretical properties of the stellar evolutionary models of the Yonsei-Yale series of Yi et al. shows good agreement between the observations and the theory at an age of about 500 Myr and a slightly sub-solar metallicity.