Timing of gamma-ray pulsars: Search in seven-parametric space

Timing of the Geminga gamma-ray pulsar is done using the data of COS B and EGRET. It is shown, that errors in angular coordinates of sources similar to Geminga strongly influence the determination of , so that at angular precision less then 10^-3 arc sec determination of the value of by means of this criterion gives an error of more than 100%. Attemps have been made to improve the coordinates of the gamma-ray pulsar using timing analysis. In addition to searching for v, and , a technique is first developed permitting the search of two angular coordinates, the absolute speed value and the direction of the proper motion. In that way, timing of gamma-ray pulsars gives an amount of information compatible with radio pulsars, but using real data gives much poorer precision. In gamma-ray sources with rare pulses the periodicity criteria are quite different from those in the radio region. Data on the coordinates and proper motion of Geminga, obtained from timing studies, do not contradict, within the errors, its identification with a G" star and its proper motion. These errors are larger than those in optical measurements, but are smaller than the corresponding errors in X-ray and -ray data. Estimation of the gamma-ray pulsar coordinates and its proper motion could be obtained independently of its optical or radio component, and are available in their absence.