Celestron C4.5 User Manual

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Aligning the R.A.
Setting Circle
32
NOTE:
Astronomy Basics
In order to align the R.A. setting circle, you must first polar align the mount.
Second, you need to know the names of a few bright stars. If you don't, they
can be learned by using the Celestron Sky Maps (#93722) or consulting a
current issue of an astronomy magazine. To align the R.A. setting circle:
1. Locate a bright star near the celestial equator. The farther you are from
the celestial pole the better your reading on the R.A. setting circle will be.
The star you choose to align the setting circle with should be a bright one
whose coordinates are known and easy to look up. (For a list of bright
stars to align the R.A. setting circle, see the list at the back of this
manual.)
2. Center the star in the finder.
3. Look through the main telescope and see if the star is in the field. If not,
find it and center it.
4. If you purchased the optional clock drive, start it now so that it will track
the star.
5. Look up the coordinates of the star.
6. Rotate the R.A. circle until the proper coordinates line up with the R.A.
indicator (the zero mark on the vernier scale). The R.A. setting circle
should rotate freely.
Once you have finished this process you are ready to use the setting circles to
locate objects in the night sky. The declination setting circle is aligned
during the process of polar alignment. There is no need to align it in the
same manner as the R.A. setting circle. Right ascension is measured in hours
and minutes. As a result, the R.A. setting circle is marked off in hours and
minutes with markers at 10-minute intervals. The hour of R.A. is printed
above the appropriate mark.
Declination is measured in degrees. The Declination setting circle, as a
result, is incremented in degrees with a marker every two degrees. Every
tenth degree is printed above the appropriate mark.
Because the R.A. setting circle does NOT move as the telescope moves in
R.A,, the setting circle must be aligned each time you want to use it to find an
object. This holds true even if you are using the optional clock drive. How-
ever, you do not need to use a star each time. Instead, you can use the object
you are currently observing.

Celestron C4.5 Specifications

General

Brand	Celestron
Model	C4.5
Category	Telescope
Language	English