Celestar Manual
Using the Drive
37
USING THE CELESTAR DRIVE
The Celestar 8 comes with a built-in single motor spur gear clock drive to track objects as they move
across the sky. The Celestar 8 is DC powered and operated by an internal 9-volt battery that is included
with the telescope. In addition, the Celestar 8 has built-in electronics that when used in conjunction with
the optional hand controller allow you to do long exposure deep-sky astrophotography.
Following is a brief description of each function.
POWERING UP THE DRIVE
The “ON/OFF” switch supplies power to the drive motor. Once on, the motor tracks at sidereal rate, that
is, the rate at which the stars move across the sky. The LED above the “ON/OFF” switch illuminates when
the drive is on.
In order for the clock drive to track accurately — across the sky from east to west — the telescope must be
polar aligned. The process of polar alignment, which was discussed earlier in this manual, makes the
telescope’s axis of rotation parallel to the Earth’s, ensuring that the telescope moves in the right direction.
Keep in mind that the clock drive moves the telescope only in right ascension at a rate that is half of the
hour hand on a clock. Therefore, the telescope makes one complete revolution every twenty four hours
and the motion is very hard to detect simply by looking at the telescope.
The drive motor in your Celestar 8 is accurate enough to keep objects in the field for long periods.
However, if you watch closely, you will notice that the object drifts slowly back and forth in right
ascension. This is known as periodic error which all telescope drives have to some degree. For visual
observing, periodic error does not pose a problem. If, however, you are interested in astrophotography,
you must use the optional hand controller to keep your subject stationary.
Figure 5-1
The cover plate for the Celestar 8 drive base.
