20
In the process of observation it is often required to perform minor
corrections in the diurnal run of the telescope. For this purpose one
makes use of handwheels 4 (fig. 0) or the buttons 3 (fig. 5) of the control
panel. The buttons 3 speed up or slow down the tracking speed of the watch
drive relative to the nominal providing the correction of right ascension
angle. The correction modes are activated when one of the buttons 3 is
pressed continuously and the indicator blinks. If the button 3 is released
the tracking speed returns to the nominal.
The telescope has high magnifications and, hence, small fields of
view, therefore it is provided with a finderscope.
After mounting the telescope it is necessary to set parallel of the optical
axes of the telescope tube and finderscope. For this purpose one should
mount a reticle with cross into the eyepiece f'=25 mm. One should make
an adjustment by remoted object.
By operating with the set screws of rings 4 (fig. ) of the finderscope
one brings the chosen remote object to the centre of the finderscope
field of view. This operation is performed once. In the future before
observation only a check-up of parallelism of the telescope and
finderscope optical axes is needed.
In order to avoid corrections of the declination axis during operation
of the watch mechanism it is required to set the telescope polar axis
in parallel to the celestial axis. In this case the northern (upper) end
of the polar axis faces the celestial pole positioned near Polaris (a
Ursae Minoris). For visual observations it is enough to incline the poral
axis at an angle equal to the latitude of the observing site and direct it
approximately along the line the South - the North. With such coarse
setting of the telescope the object will “deviate” step by step in declination
(it is lifted or lowered in the field of view). This error is corrected at times
by means of the micrometer screw of the declination axis.
For photographic operations and in the case when the telescope can
be set stationary, the polar axis of the telescope should be set precisely.
For this purpose one observes any bright star in the East, then in the
South and makes notice of the direction of the star displacement.
If in observation of the star in the East it is displaced in the telescope
field of view so that in its tracking the upper end of the telescope tubes
sinks slowly, the north end of the polar axis should be somewhat
lifted.
If the upper end of the tube is lifted step by step, the north (upper) end
of the polar axis should be lowered.
For precise setting of the axiss by azimuth one observes the star
near the meridian circle (above the south point) in the same way.
If in the star tracking one has to lower slowly the upper end of the
