Filter
Top Products
Astronomy Basics • 39
Polar Alignment Finders
There are two finders specifically designed for polar alignment that can be used
with the CG-4 and CG-5 mounts. These finders can be purchased as optional
accessories for the C150-HD and G-8N. The first finder, known as the 7x50 Polaris
finder (#51614), is used as a regular finder.
The second finder is the polar axis finderscope (#94221). Its sole purpose is polar
alignment and can NOT be used to find objects in the telescope. Both these finders
work on the same principle, but their methods of operation are slightly different.
These methods are generally easier than those already described and they are fairly
accurate. For more information on both these finderscopes, refer to the Optional
Accessories section of this manual or ask for the Celestron accessory catalog
(#93685).
Aligning the R.A.
Setting Circle
Before you can use the setting circles to find objects in the sky you need to align the
R.A. setting circle. The declination setting circle is aligned during the polar
alignment process. In order to align the R.A. setting circle you will need to know
the names of a few of the brightest stars in the sky . If you don’t, they can be
learned by using the Celestron Sky Maps (#93722) or consulting a current as-
tronomy 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. Start the optional motor drive so that it will track the star. If you are not using
a motor drive the star will start to drift out of the field and you will need to
center it again before setting the R.A. circle.
5. Look up the coordinates of the star.
6. Rotate the 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.
As mentioned above, the declination setting circle is aligned during the pro-
cess of polar alignment. There is no need to align it in the same manner as
the R.A. setting circle.
Once you have finished this process you are ready to use the setting circles to
locate objects in the night sky. See the section on “Using the Setting Circles”
for specific information.