  The reconstruction of extensive air showers (arrival direction, core position
and energy estimation) by the surface detector of the Pierre Auger Observatory
is discussed together with the corresponding accuracy. We determine the angular
reconstruction accuracy as a function of the station multiplicity by using two
different aproaches. We discuss statistical and systematic uncertainties in the
determination of the signal at 1000 m from the core, S(1000), which is used to
estimate the primary energy.
