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FINDING CELESTIAL OBJECTS
Once your telescope is polar aligned, you must set the hour circle in order
to use the measurements listed on the mount to nd celestial objects. Once
the hour circle is properly set, you will be able to use the coordinates listed
on star charts to nd objects for viewing in the night sky. Setting the hour
circle will require that you recognize and be able to nd a star other than the
ones used for alignment of the telescope.
To set the hour circle, use a star which you are able to easily identify and
have the coordinates for. In the Northern Hemisphere, Dubhe is a recogniz-
able star which can be used for this. Dubhe is the pointer star in the Big Dip-
per closest to Polaris and lies at 58°42’ Dec., 11h23m R.A.. In the Southern
Hemisphere, Acrux is an easy to find star for setting the hour circle. Acrux is
the closest star to the southern celestial pole in the Southern Cross and lies
at -63°15’ Dec., 12h33m R.A..
SETTING THE HOUR CIRCLE
1. Loosen the declination clamp and rotate the telescope to the nearest de-
gree of declination to the star you will be viewing (58° for Dubhe, -63° for
Acrux). Retighten the clamp to lock the declination in place.
2. Loosen the right ascension clamp and rotate the telescope on the R.A.
axis until the star you are using to set the hour circle is near the center of the
nderscope. Retighten the clamp to lock in the R.A. axis.
3. Center the star in the eyepiece using the R.A. and Dec. adjustment cables.
Once it is centered, turn the hour circle until the arrow points at the ap-
propriate measurement for the star you are looking at (11h23m for Dubhe,
12h33m for Acrux). This sets the hour circle to the appropriate setting for
your viewing location and time.
USING SETTING CIRCLES
With the telescope polar aligned and the hour circle set, you can find celes-
tial objects using star charts available in books or on the web. A star chart
will normally consist of a map and an ephemeris. The ephemeris will tell
you the celestial coordinates of an object. By using the hour circle and the
declination circle, you can point your telescope at the objects you see on
the star chart quickly and easily. You will probably need to fine tune your
aiming with the adjustment cables when you view a new star, but the use of
celestial coordinates will make finding the objects you would like to look at
considerably easier.