LX-200
Polar alignment using the drift method
The LX-200 has the ability to enable users to "train" out the Periodic Error, otherwise known as Periodic Error Correction.
This process enables one to manually make corrections in software so that imperfections in the mechanics of the RA drive can be removed. This is subject to "operator error" and would better be done automatically.
Using a CCD in guide mode, one can make a more effective PEC adjustment. The process I have used for this is as follows:
1. Make sure your telescope is Polar aligned accurately (I use drift alignment for this)
2. Set up CCD as a guider and adjust controls/exposure so that corrections to the telescope are made every second.
3. Start guider running on a star @ 20 EL and as close to South as you can.
4. On your LX-200 keypad Select SMART, then Erase, then Learn.
5. With you telescope still being guided, wait for the SMART drive to start beeping, this is indicating that it is learning the corrections being made by the guider.
6. Monitor closely the guiding process.
7. When the beeping has finished, the Periodic error has been trained.
8. Stop guiding, start imaging !
When I started in astrophotography, I used the iterative method of polar aligning, but quickly found out that I was fighting against slight GOTO errors in the LX-200 system and on some occasions took over an hour to get aligned, even then I would end up with enough mis-alignment to limit my imaging to 30 seconds or less. I finally took the plunge into the drift alignment method and have been really pleased with my results. The process is as follows.
1. Roughly polar align, use whatever process is easier for you, I just make sure I can line Polaris up in my finderscope.
2. GOTO a star pointing South and at about 20 degrees elevation to avoid atmospheric disturbances.
3. Insert an illuminated Reticule that gives you approximately 200x magnification into your diagonal.
4. Adjust Reticule so that the cross hairs are aligned with your telescope drives.
5. Center star in an illuminated reticule.
6. If star drifts UP (North) in the reticule, adjust wedge in Azimuth (East West) so that the star moves RIGHT in the reticule.
If star drifts DOWN (South) in the reticule, adjust wedge in Azimuth so that the star moves LEFT in the reticule.
7. Recenter star using keypad.
8. Repeat 6 & 7 until no drift is perceived for 5 minutes.
9. GOTO a star pointing East or West at about 20 degrees elevation.
10. Center star using keypad.
11. For a star in the East, if star drifts UP, adjust wedge Elevation (North South) so the star moves DOWN,
if star drifts DOWN, adjust wedge Elevation (North South) so the star moves UP.
12. For a star in the West, if star drifts UP, adjust wedge Elevation (North South) so the star moves UP,
if star drifts DOWN, adjust wedge Elevation (North South) so the star moves DOWN.
13. Recenter star using keypad.
14. Repeat 12-13 until no drift is perceived for 5 minutes.
15. If a large adjustment is made in steps 12-13, then it may be necesarry to go back to step 2.