Finding the population of pulsars in the Milky Way galaxy requires a knowledge of the parameters and limitations of the various surveys made with different instruments and in different regions of the sky. We list the available survey data and show how models of the galactic population can be compared with the observational data, allowing estimates of pulsar birthrate and lifetime. Determination of accurate positions of individual pulsars require a Solar System ephemeris and a complex geometrical computation. Binary pulsar orbits display reletivistic effects which can be measured with remarkable precision to yield parameters of orbits and checks on relativistic theory.

Precision timing of pulses is at the heart of pulsar research. Pulse arrival times can be measured to an accuracy of only a few metres travel time, and analysis must take account of pulsar positions and the Earth’s orbit, the Römer correction to the barycentre, and General Relativistic corrections. Pulsar timing contributes to the comparison of fundamental positional reference frames. Timing provides periods and period changes on short and long time scales, giving pulsar ages and proper motions. The precision timing of some millisecond pulsars is comparable to the best terrestrial laboratory clocks.