Modern tasks of high precision astrometry demand optical coordinate systems
including more faint stars than are available now in current conventional
systems (HIPPARCOS). For this purpose it is suggested to use old
photographic observations accumulated in the Pulkovo Observatory. Extensive
observational data have been obtained at Pulkovo Observatory during the
last century in the framework of several programs, e.g. Pulkovo Galaxy
Plan, etc. Observations have been made at the Normal Astrograph from 1894
to the present. The data are investigated with the aim of extending the
Hipparcos catalogue to faint stars beyond 11th stellar magnitude. All
available observations are taken into account. A description of the
considered material is given. The distribution of the selected plates over
the celestial sphere is shown as well. Coordinates of faint stars in the
HIPPARCOS system are calculated for selected areas. The accuracy of
computed star coordinates is analysed. Results of the investigation are
presented.