Precise Polar Alignment for Celestron CPC 1100 with a Mitty Wedge
The Mitty wedge for the Celestron CPC 1100 XLT telescope is well engineered and solid as a rock, however, Mitty provides no instructions how to use the wedge and there are no markings on the dials indicating which way to turn them to increase or decrease DEC or RA. For a novice, such as myself, this resulted in hours of research and much frustration. Hopefully, if you have recently purchased a Mitty wedge for your telescope or are thinking about buying one, this document will save you considerable time. Following this alignment procedure I have been able to track a star in the cross hair of the Orion 12mm Plossl illuminated reticle for 30 minutes with no apparent movement. I was also able to keep the Orion Nebula Trapezium four stars in the cross hair square for 45 minutes with no apparent movement. I think this alignment should be excellent for prime focus long exposures using the Orion Starshoot Pro V2.0 Deep Space CCD imaging camera and the Orion StarShoot Autoguider both mounted to the Orion Deluxe Off-Axis Guider. One of the biggest problems I experienced with the wedge is remembering what to do next according to what I did last. Let me explain. When performing a precise polar alignment using the drift method, one must align a star in the cross hair of an illuminated reticle and monitor the drift of the star. For example, watching a star in at the intersection of the Meridian (+- hour) and Celestial Equator (+-5 degrees), if the star drifts north, the polar axis is too far west so the wedge needs to be adjusted to the east. While watching a star in the East (or west) 20 degrees above the horizon and +- 5 degrees of the celestial equator, if the star drifts north the polar axis is too high and the Mitty DEC must be adjusted to lower the telescope (Latitude is to high). Each of these adjustments, RA east-west and DEC north-south affect each other slightly so the procedure needs to be repeated several times. Referring to the polar alignment instructions in the CPC 1100 manual, it is easy to remember what to do if the eastern star drifts north or the meridian star drifts south, but then remembering which Mitty dial to turn and in which direction can become confusing. I suspect this becomes second nature after doing it many times, but I decided to write this document for myself and the benefit of others so they can decrease their learning time. This document is not all inclusive and only describes the process of polar aligning the wedge. For other steps, such as telescope EQ-North alignment, please refer to the Celestron CPC 1100 manual. I have provided this documentation because Mitty only provides four photos showing how to attach the mount to your tripod and nothing explaining how to adjust the mount. In order to obtain a precise polar alignment for the CPC 1100 XLT mounted on a Mitty wedge the following items are required: 1) Celestron CPC 1100 XLT w/ Tripod 2) 9x50 Finder Scope

3) 4) 5) 6)

Mitty Wedge Illuminate Reticle (yeah, I tried before I bought one! Get an Orion 12mm Plossl Illuminated) Patience Practice
In order to obtain a precise polar alignment for the CPC 1100 XLT mounted on a Mitty wedge the following steps are required in order: 1) Mount the wedge to your tripod. The instructions are provided with the wedge. When the wedge is properly mounted the wedge should be mounted in a manner that aligns the wedge and telescope with one of the three tripod legs. This will be referred to as the North facing leg. 2) Point the north facing leg of the tripod north. If doing this at night, from the northern hemisphere, position the tripod so the north facing leg is pointing directly at Polaris. The more accurate you align the tripod the easier it will be to align the wedge. 3) Level the tripod. This is very important. It is much easier to level the wedge before you mount the telescope. Once you mount the telescope, lifting a leg is much heavier and the scope fork arms prevent you from looking directly over the level bubble. I recommend precisely leveling the wedge as best as you are able. Adjust the tripod legs so the wedges bubble is precisely in the center. Getting it in the circle but not centered will affect your polar alignment. 4) Mount your telescope to the wedge. This is best accomplished with two people. I have successfully mounted the telescope by myself on several occasions, but it is always better to have assistance. I am 48, 511 240lbs. I am a big guy. GET HELP! 5) Align your telescope and finderscope. I also purchased a Lumicon Laser and mount. I get all three precisely aligned aiming at my neighbors outside brick wall! At night, try using a dim star you can see with the naked eye. If you dont align your finder scope accurately you will have trouble locating your alignment stars in the 12mm illuminated reticle. 6) Set the DEC (ALT) on the Mitty wedge to your Latitudei. The adjustment is on the back (south) of the wedge. There are Latitude markingsii on the inside (west) of the wedge. Set the DEC adjustment as close to your latitude as possible. The markings are 1 degrees each with a label every 2 degrees. In other words, you will see 32, 34, 36, 38, 40, etc., with a mark in between each labeled mark. My latitude is 36.87 so I set my DEC exactly between the 36 mark and the unlabeled mark just above it. This doesnt have to be precise but the closer you are too precise the less time it will take to perform the drift alignment. 7) Adjust (using the dials on either the east or west side of the wedge) the RA (right ascension) so that the front bolt is in the center of its slotiii. This will allow plenty of travel east or west during your drift alignment. Note that turning a dial on one side results in the opposite rotation of the dial on the opposite side of the mount. 8) Refer to your Celestron Manual to perform an EQ-North alignment (or EQ-South if you live in the southern hemisphere). This procedure is fairly simple and straightforward. When you mount your CPC 1100 it will be roughly pointing north and angled near Polaris. Press align, select EQNorth alignment, press enter, then press enter to accept the site/time information. Select EQ Autoalign and press enter. The scope will tell you to line up the Alt-Index markers. Use the hand

controller to point the scope tube (OTA) at the ground and line up the Alt-Index markers on the west side fork arm. Press enter again and then using only the Az (left or right) arrows to rotate the scope 180 degrees to point it at the Meridian. If you are doing this correctly, only the fork arms should move, not the OTA. When you are pointing at the Meridian press align and the CPC will select two alignment stars. Press enter the CPC will slew to the first star. It the star is obstructed, just press undo and select another star from the list. Use the finder scope to center the first star then press enter, then use the illuminated reticle to center the star precisely and press align. The CPC will then ask to slew to the second star, press enter. When the CPC slews to the second star, once again do a rough alignment with the finder scope (make sure your rough alignment is good enough to get the star into the illuminated reticles field of view) then press enter. Center the second star precisely in the cross hairs of the reticle and press align. There you have it, you have a pretty good alignment, but not nearly good enough to do astrophotography! 9) Next is the drift alignment. This procedure is also in the CPC manual, but this procedure is the reason I created this document. The Mitty wedge doesnt provide any indicators or instruction about which way to turn the dials to move the mount. The images I have taken below, along with the arrows shows precisely what to adjust and what affect it will have on your alignment. The CPC drift alignment from the CPC manual is provided below for your convenience along with my notations for the Mitty wedge: Declination Drift Method of Polar Alignment This method of polar alignment allows you to get the most accurate alignment on the celestial pole and is required if you want to do long exposure deep-sky astrophotography through the telescope. The declination drift method requires that you monitor the drift of selected stars. The drift of each star tells you how far away the polar axis is pointing from the true celestial pole and in what direction. Although declination drift is simple and straight-forward, it requires a great deal of time and patience to complete when first attempted. The declination drift method should be done after any one of the previously mentioned methods has been completed. To perform the declination drift method you need to choose two bright stars. One should be near the eastern horizon and one due south near the meridian. Both stars should be near the celestial equator (i.e., 0 declination). You will monitor the drift of each star one at a time and in declination only. While monitoring a star on the meridian, any misalignment in the east-west direction is revealed. While monitoring a star near the east/west horizon, any misalignment in the north-south direction is revealed. It is helpful REQUIRED to have an illuminated reticle eyepiece to help you recognize any drift. For very close alignment, a Barlow lens is also recommended since it increases the magnification and reveals any drift faster. When looking due south, insert the diagonal so the eyepiece points straight up. Insert the cross hair eyepiece and align the cross hairs so that one is parallel to the declination axis and the other is parallel to the right ascension axis. Move your telescope manually in R.A. and DEC to check parallelism.

First, choose your star near where the celestial equator and the meridian meet. The star should be approximately within 1/2 an hour of the meridian and within five degrees of the celestial equator. Center the star in the field of your telescope and monitor the drift in declination. If the star drifts south, the polar axis is too far east. Mitty Adjustment- Image 2: If you use the east side Az (RA) knob, turn the knob counterclockwise (green) to move the mount west. If you use the west side Az (RA) knob, turn the knob clockwise (green) to move the mount west. If the star drifts north, the polar axis is too far west. Mitty Adjustment- Image 2: If you use the east side Az (RA) knob, turn the knob clockwise (red) to move the mount east. If you use the west side Az (RA) knob, turn the knob counterclockwise (red) to move the mount east.
Make the appropriate adjustments to the polar axis to eliminate any drift. Once you have eliminated all the drift, move to the star near the eastern horizon. The star should be 20 degrees above the horizon and within five degrees of the celestial equator. If the star drifts south, the polar axis is too low. Mitty Adjustment- Image 1: Using the DEC knob in the back of the wedge, turn the knob counterclockwise (green) to move the mount up. If the star drifts north, the polar axis is too high. Mitty Adjustment- Image 1: Using the DEC knob in the back of the wedge, turn the knob clockwise (red) to move the mount down.
Again, make the appropriate adjustments to the polar axis to eliminate any drift. Unfortunately, the latter adjustments interact with the prior adjustments ever so slightly. So, repeat the process again to improve the accuracy checking both axes for minimal drift. I do this three times, twice initially for 5 minutes on each for the first two stars (South and East). The third and final adjustment I monitor the stars for about 15 minutes, since I have already removed most of the drift on the first two adjustments. Once the drift has been eliminated, the telescope is very accurately aligned. You can now do prime focus deep-sky astrophotography for long periods. NOTE: If the eastern horizon is blocked, you may choose a star near the western horizon, but you must reverse the polar high/low error directions. Also, if using this method in the southern hemisphere, the direction of drift is reversed for both R.A. and DEC. Thats it, once you have completed this process, your CPC 1100 and Mitty Wedge are precisely polar aligned and you can accurately track objects for long periods with little to no drift. Have fun and dont forget to share your images!

Image 1 DEC Adjustment

Image 2 RA Adjustment
Refer to Image 1 DEC Adjustment. There are two hex bolts on each side (east/west) of the wedge that must be loosened in order for the DEC dial to be adjusted. Each of these bolts are mounted in slots allowing full travel of the wedge DEC plate. ii Refer to Image 2 RA Adjustment. There are three hex bolts on the bottom of the wedge that must be loosened in order for the RA dials to be adjusted. Each of these bolts are mounted in slots allowing full travel of the wedge in RA. iii Refer to Image 2 RA Adjustment. There are three hex bolts on the bottom of the wedge that must be loosened in order for the RA dials to be adjusted. Each of these bolts are mounted in slots allowing full travel of the wedge in RA.