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