ASTROMETRY WITH A SHORT-FOCUS CCD-ASTROGRAPH

		I.S.Guseva
	    Pulkovo Observatory

     Some results  on astrometry  with  a short-focus astrograph
(D=100 mm, F=712 mm) equipped with Russian CCD ISD015A (Electron,
St Petersburg) will be presented. The size of the CCD is 520*580
pixels 18*24 micron, consequently, field of view is 45*67 arcmin.
    Two reasons give us the background to deal with such a small
instrument. The first is  a successful realization  of the TYCHO
project, which  will provide  the ground-based observations with
a dense set  (~ 25 stars  per square degree)  of reference stars
of high precision (~ 30 mas). The second is that the application
of CCDs  allows  to increase  both  the precision of astrometric
observations and  the limit of stellar magnitudes. Even with our
small instrument  we can observe  the stars fainter  than 16 mag.
Both reasons allow to solve many tasks of traditional astrometry
with rather small CCD-astrographs.
    Investigation of the CCD performance is especially important
in the case  of short-focus optics. The appropriate technique of
observations and data reduction is developed.
     The program  of observations  includes  some open clusters
(standard astrometric fields), minor planets and other objects.