Latitude Scales - Celestron Ultima 11 Instruction Manual

Latitude Scales

The easiest way to polar align a telescope is with a latitude scale. Unlike other methods that require finding
the celestial pole by identifying certain stars near it, this method works off of a known constant to determine
how high the polar axis of the telescope should be pointed. The wedge that comes with your telescope has a
latitude range of 0 to 90º.
The constant, mentioned above, is a relationship between your latitude and the angular distance the celestial
pole is above the northern horizon. The angular distance from the northern horizon to the north celestial
pole is always equal to your latitude. To illustrate this, imagine that you are standing on the north pole,
latitude +90°. 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. This constant between the celestial pole and the horizon also
works for the southern hemisphere. However, the angle is then measured from the southern horizon.
If you are observing from Los Angeles, which has a latitude of 34°, then the celestial pole is 34° above the
northern horizon. A latitude scale points the polar axis of the telescope at the right elevation above the
northern (or southern) horizon.
To align your telescope:
1. Make sure the polar axis of the mount is pointing due north. Use a landmark that you know
faces north.
2. Level the tripod by adjusting the length of the tripod legs. There is a bubble level built into
the mount for this purpose.
NOTE: Leveling the tripod is only necessary if using this method of polar alignment. Perfect
polar alignment is still possible using other methods described later in this manual without
leveling the tripod.
3. Adjust the mount in altitude until the latitude 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 you will make when
tracking an object. It is accurate enough for short exposure prime focus planetary photography (a couple of
seconds) and short exposure piggyback astrophotography (a couple of minutes).
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