Celestar Manual
Astronomy Basics
33
Latitude Scale Polar Alignment Method
The easiest way to polar align a telescope is with a latitude scale. Unlike other methods that require you to
find the celestial pole by identifying certain stars near it, this method works off of a known constant,
latitude, to determine how high the polar axis should be pointed. The latitude range for the Celestar
telescope is 0° to 90°.
NOTE: If the altitude of the scope needs a minor adjustment for polar alignment, be aware that the
telescope tends to fall toward the observer when the four screws, that hold the tilt plate, are loosened.
Be sure you are holding the telescope!
If you know the latitude of your observing site then you can determine the altitude the tilt plate needs to be
set at. There is a relationship between your latitude and the angular distance (altitude) the celestial pole is
above the northern (or southern) horizon. The angular distance from the northern horizon to the north
celestial pole is always equal to your latitude. In other words, the altitude you need to set your tilt plate at
is the same as the latitude of your observing site.
To illustrate this, imagine that you are standing on the north pole, la90°. The north celestial pole,
which has a declination of +90°, would be directly overhead (i.e., 90 above the horizon). Now let's say that
you move one degree south. Your latitude is now +89° and the celestial pole is no longer directly
overhead. It has moved one degree closer toward the northern horizon. This means the pole is now 89°
above the northern horizon. If you move one degree further south, the same thing happens again. As you
can see from this example, the distance from the northern horizon to the celestial pole is always equal to
your latitude.
If you are observing from Los Angeles, which has a latitude of 34°, then the celestial pole would be 34°
above the northern horizon. All a latitude scale does then is to point the polar axis of the telescope at the
right elevation above the northern (or southern) horizon. To align your telescope:
1.
Point your telescope due north. Use a landmark that you know faces north.
2.
Set the Wedgpod on a level surface with legs fully separated.
3.
Adjust the Wedgpod’s tilt plate in altitude until the latitude indicator (the hex head bolt serves as the
indicator) points to your latitude.
This method can be done in daylight, thus eliminating the need to fumble around in the dark. Although
this method does NOT put you directly on the pole, it will limit the number of corrections needed when
tracking an object. It will also be accurate enough for short exposure prime focus planetary photography (a
couple of seconds) and short exposure piggyback astrophotography.
Pointing at Polaris Method of Polar Alignment
This method uses Polaris as a guidepost to the celestial pole. Since Polaris is less than a degree from the
celestial pole, you can simply point the polar axis of your telescope at Polaris. Although this is by no
means perfect alignment, it does get you within one degree. Unlike the previous method, this must be done
in the dark when Polaris is visible.
1.
Set the telescope up so that the polar axis is pointing north.
