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ALTITUDE AND AZIMUTH ADJUSTMENTS – ROUGH POLAR
ALIGNMENT
It is recommended that you not attach the RAPAS until you have roughly centered Polaris through the site hole.
For rough polar alignment, your goal is to sight the
celestial pole when looking through the polar alignment
sight hole. You will need to make altitude (up/down) and
azimuth (side-to-side) adjustments to the position of the
mount.
[An inclinometer and a compass adjusted for magnetic
declination at your location (or these functions on a smart
phone app) can be very helpful for daytime setup. In
addition, be sure to learn the Daytime Polar Alignment
Routine as described in the keypad manual. It is a great
method for rough alignment!]
Note on Bubble Levels:
It is possible to achieve
perfect polar alignment without having the pier level, but
it is slightly more difficult. With a pier that is not level,
each adjustment in azimuth also causes a minor shift in
altitude and vice versa. This is why we have included
the bubble level on the 1100GTO. However, don’t waste
time obsessing about having the pier perfectly level. This is, after all, NOT an Alt / Az mount! Devote the time to the actual
polar alignment instead. If you are reasonably close to level, you will not be able to notice a difference. Keep in mind that
unless you are a serious astrophotographer or imager, “perfect” polar alignment is not critical.
1. Remove the Dec. axis sight hole cover, to complete these steps. Examine the polar axis assembly and you will see
that the center of the R.A. shaft is hollow.
2.
Azimuth adjustments:
Depending upon how accurately you
positioned your mount when setting up, you may need to move or
turn the entire pier or tripod east or west until Polaris can be seen
through the sight hole. If Polaris is already in view, you will use the
two fine azimuth adjustment knobs, one on each side of the mount,
to center it.
You must back off the opposing azimuth knob in order
to move the other knob in that direction.
One full turn of the azimuth knob is approximately 0.668
degrees (40.5 arcminutes). Small graduations are 1.62
arcminutes; long graduations are 8.1 arcminutes.
The best adjustment technique to use with the Astro-Physics Azimuth Adjuster, with its clear registration marks for fine
adjustment, is to back off one of the knobs by a set amount (a certain number of registration marks) and then to turn the
other knob until you re-establish contact on both sides of the Azimuth Adjuster Block. You can very precisely zero in on the
desired position with no backlash or ambiguity on the position. You can also always go back to the precise starting point
if for some reason you overshot your mark (or if you adjusted the wrong way), because you know exactly how far you’ve
gone. This is explained further in the section on Fine Polar Alignment.
3.
Altitude (latitude) adjustments:
Loosen the Altitude Lock Knobs. Move the polar axis up or down with the large
Altitude Adjustment Knob located in the front of the polar axis assembly.
One turn of the altitude knob is approximately 0.6031 degrees (36.1 arcminutes).
4. Continue your azimuth and altitude adjustments until you center Polaris in the polar alignment sight hole. At this point,
you have achieved a rough polar alignment, which may be sufficient for very casual visual observations, if you are not
planning to slew to target objects. When the R.A. motor is engaged (the power is plugged in), it will compensate for the
rotation of the earth and keep the target object within the low power eyepiece field of view. Your target object will slowly
drift since polar alignment at this stage is only approximate. However, you can make corrections with the N-S-E-W but-
tons of your keypad controller.
5. Tighten the Altitude Lock Knobs by hand.
Azimuth Block
Azimuth Adjuster Knobs
Azimuth Threaded
Push Rod