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Polar Align Your Telescope, Here's How.
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Polar Align your Telescope, Here's How.
"How to Polar Align"

by
Craig Hill



The Equatorial Mount

Balancing the Declination Axis
The first thing we need to do is set the scope on the mount, and balance it. Put your weight on the mount, then the scope. As you look at the mount, you will see the two setting circles on it. One right under the scope tube is the Declination Setting Circle.




There are also screws to hold the two major axis' tight. Make sure the screw that holds the axis with the weight is tight, and then loosen the screw that will allow the scope to turn. Next, move the scope back and forth in it's mounting rings until you can move it to any position, and it stays where you leave it. Try to do this part with an eyepiece and any other accessories you may be using attached to the scope, so as to get an accurate balance.

Balancing the Right Ascension Axis
Next, we want to tighten the Declination Axis screw, and loosen the other one, for balancing the Right Ascension Axis. The Right Ascension, or R/A axis, is the one that your weight is screwed into. The other setting circle here is for this axis. R/A Setting Circle Once we have loosened the screw holding this axis, we want to get the weight adjusted so that the scope can swing from side to side, again, staying in place wherever you place it. Balancing the scope saves wear and tear on your mount's gears, and allows for easy movement when looking for objects. You never really loosen the dscrews all the way up, but just enough so that the scope moves with just a slight resistance on either axis. Usually, once you have balanced the R/A axis, the weight need not be moved again, so when you take the scope down, just un-screw the weight, shaft and all, and store it this way. This is a picture of balancing the Right Ascension Axis
And finally, a picture showing The Final Balance


Aligning to the North Star
Ok..Now that we have the scope balanced so that it will move in either direction freely, and stay put wherever we let go of it, it's time to "Polar Align" it. First, we will need to set the "Latitude Adjustment" to our particular Latitude, which can be obtained by calling a nearby airport, and asking what the latitude is for your area. The object of adjustment to the latitude, is to have the scope point right at the North Star when the Declination axis is set to 90 degrees, and the R/A axis is set to your latitude. While aligning the scope to the North Star, have the weight pointing straight down also. Now... all scopes' latitude adjustment scales are not accurate, and there are always "differences" in actual latitude and the setting scale.. SO... with the declination setting circle set exactly to 90 degrees, and the weight pointing straight down, BOTH axis' LOCKED at this point, simply move the Latitude adjustment until the North Star is centered in the scope. You may have to move the base of the mount, or the whole tripod to one side or the other now to center the North Star. The closer you can get the North Star to the center of the eyepiece, the better the mount will track, and the more accurate the setting circles will be for finding objects by their "Celestial Coordinates". Also important, is to have the base of the mount level. This can be accomplished by using a small level, and adjusting leg heights until the base is level. Most mounts have a screw stop for the Latitude adjustment on them. Once you have set the Latitude, it's a good idea to set this stop screw so that the scope doesn't "creep down" during your observing session. Now that you have completed this process, (and just so that you know, when you actually do this set-up a few times, it will take mere minutes to complete), we are ready to track objects that we find by simply turning only the gear on the R/A Axis. As the object moves across the sky, simply turn the R/A axis, and follow it. This is also the axis a motorized mount would move. VERY IMPORTANT!! As you use the scope to find objects, NEVER move the base of the mount once it is aligned, and NEVER allow the weight to be in a position higher than the scope tube, as it may slide down and damage the scope or mount. If the weight seems to want to become higher then the scope, you have to turn the scope around on the mount, and then rotate the tube. REMEMBER.. the Polar Axis MUST remain pointing at the North Star. Also be careful that the eyepiece does not fall out of the scope as you turn it.



A Graphic representation of Polar Alignment
and the Celestial Sphere.

Using the Mount to Locate Objects
Now that we are all set up, balanced and Polar Aligned, we can use the mount to find objects by their "Celestial Coordinates". First, you will notice that the Declination Setting Circle does NOT rotate. It is set at the factory, and needs to remain where it is. The Right Ascension Setting Circle DOES rotate, and is changed when we use it to find objects. To begin, we must first set the scope to a star with a known address. We will use a "circumpolar star", or one that is visible all year long from a Latitude of 40 degrees North... Beta Ursa Major, or Merak. This star is the bottom right star of the bowl of the Big Dipper. Its Celestial Coordinates are..11 hours, 1 Minute of R/A.. so.. we get this star in the center of our eyepiece, and quickly set the R/A setting circle to 11 Hours. The numbers on this circle represent hours and minutes. on my mount, the divisions are in 10 minute increments. The declination of this star is +56 degrees.. 23 minutes. This should already be where the declination circle is, if you have set up the mount properly. Now, moving quickly, because as the stars move across the sky, the R/A moves with them, find the coordinates of an object you wish to find, and move the scope on its two loosened axis' until both the R/A setting circle, (without touching the R/A circle) AND the Declination circle read the star's address. If you have done everything correctly, the object should be in or near the center of the eyepiece in the scope. You MAY need to move the scope around just a LITTLE to find the object, but it will be very near to where you are pointing the scope.

As I said in the beginning, this page is simply intended to help the new person understand how to use an Equatorial Mount. If you have ANY questions, or something does not seem clear,
PLEASE E Mail me at Craig
It is my intention to make this page as easy to understand as possible. Your comments are really appreciated, Thanks!! And Clear Skies!!

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