Celestron CR-150 HD - Manual (Page 35)

Astronomy Basics • 35
Polar Alignment Finders Polar Alignment Finders Polar Alignment Finders Polar Alignment Finders Polar Alignment Finders
There are two finders specifically designed for polar alignment that can be used with
the CR-150 HD telescopes. These finders can be purchased as optional accessories
for the CR-150 HD. The first finder, known as the 7x50 Polaris finder (#93785-
8P), 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. Aligning the R.A. Aligning the R.A. Aligning the R.A. Aligning the R.A.
Setting Circle
Setting Circle Setting Circle Setting Circle 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 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. 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.