Iterative Polar Alignment


This method of polar alignment is reasonably fast, simple, and should work with most any polar GOTO scopes and mounts such as the Meade LX200 Classic, LX200GPS, ETX, Orion Atlas, Celestron, Losmandy, Astrophysics, LXD55's, etc. In other words, I have used the technique on German Equatorial Mounts as well as Fork Mounts and found that the result is accurate enough for CCD imaging.  I have achieved integrations up to 1 minute at f/6.3 and nearly 2 minutes at f/3.3 using this method. At first reading, this technique may seem complicated but I assure you that once you get used to it, it is very fast and accurate. I can usually get polar aligned in about 20-minutes using this method.

Before performing the procedure below, adjust your finder scope as accurately as you can. This only takes a couple of minutes and will help with the alignment process
Iterative Polar Alignment Procedure:

1) Perform a rough polar alignment (i.e. per the Meade manual, but you can skip the part that tells you to get the stars rotating in nice circles when moving the scope in RA).

2) Select 1-STAR ALIGNMENT in the Autostar menu. Make sure that Autostar picks an alignment star well away from the RA of Polaris (2 hours 30 minutes) and GOTO it. (If Autostar selects a star that is not at least 3-hours from the RA of Polaris, select a different star).

3) Center the alignment star as usual (using the keypad) and press ENTER to synchronize on it. At this point, Autostar will probably tell you "align successful".

4) Use Autostar to select Polaris and do a GOTO. When the GOTO is complete, Polaris will probably NOT be centered, or possibly not even in the field of the eyepiece on the first iterations. That's OK...use the finder.

NOTE: In the step below, I have found that if you do synchronize on Polaris, it will not goof-up the result. Just keep going and the sequence still converges.

5) Using only the controls on your wedge (NOT the keypad), adjust the wedge to move Polaris about 1/2 to 2/3 the distance needed to center it. (Do NOT synchronize on Polaris, and do not exactly center Polaris in this step!)

6) Using the keypad, do a GOTO on the alignment star selected in Step 3) above.

7) Center the alignment star using the keypad and synchronize on it.

8) Repeat Steps 4), 5), 6) and 7) above until Polaris and the "alignment star" are centered when you do the GOTO's.

Troubleshooting, Pitfalls and Traps:  

The only problem I have encountered using this method, and you may too, is that the sequence sometimes does not converge. That is, your GOTO's keep "hopping around" and landing on one side or the other of Polaris and the alignment star.  If this occurs, it is most probably because the alignment star has the same, or nearly the same RA as Polaris (2hrs 30min). It is best to choose an alignment star that is well away (i.e. 3-hours or more) from the RA of Polaris. If Autostar picks an alignment star with nearly the same RA as Polaris, the sequence probably will not converge. What's worse, the sequence may *appear* to converge because the GOTO's may center both Polaris and the alignment star, but there can still be a large polar alignment error. The star Hamal is a perfect example of a star NOT to use as an alignment star.

Bottom line...Make sure that the alignment star you use is more than 3 hours away from the RA of Polaris. If you do this, there should be no problems.

Finally....
You can "tweak" your alignment using the drift method if you want to be even more precise, but I find that it is typically not necessary.