The Palign2 program is a utility to help you align your polar mount telescope. Given the coordinates of two stars and the error you found in moving from star 1 to star 2, the program will compute the error in the azimuth and elevation of the telescope's mount. This is the information you need to tweak the mounting alignment. If you have a Meade LX-200 telescope the program is able to automate the moving of your scope and reading of its current position, making the process even faster.
Most mount alignment procedures require you to find Polaris or have a view of the horizon. This utility does not need that, though the precision is improved the farther apart star 1 and star 2 are located. Alignment becomes an interative process, each step giving you advice on how to adjust the telescopes mounting. I've been able to adjust my telescope mount to within an arcminute working with 2 stars in the constellation Leo, which is all I can see through the trees of my viewing site.
The formulas for translating the RA/Dec error to mount zimuth/elevation were published by Ralph Pass: "2 star Polar Alignment" (http://rppass.com/align.pdf) The program offered here merely implements the formulas in a format that is relativly easy to use. Thank you Ralph!
The program is offered as freeware with the usual lack of any warranty and advisement that you use it at your own risk. Be careful of any software that is going to slew your telescope, keeping your hand at the power cutoff until you get comfortable with the program and learn how to use it and trust it.
I would ask that if you use it, please drop me a note. Kudos and complaints and suggestions for improvements should be sent me, George Silvis, at PAlign2@GASilvis.net .
Notes on using the program:
The program has two Modes: If "TestMode" is checked, the program does not attempt to control your telescope via the serial port. You enter the the RA/Dec error you observed swinging from star 1 to star 2, input the sidereal time and hit Button 3 to have the error computed
If "TestMode" is not checked then you are in Automatic mode and the program will communicate with the telescope if it uses the Meade LX200 interface.
preparation:
- Your telescope should have its observing location set.
- Your telescope should have its sidereal time set.
- Identify the 2 stars that you will be using. Input their coordinates into the form or select the star by the LX200 number.
process: 1- Button 1 will command the scope to goto the coordinates of star 1. 2- Move the scope manually till it is pointing at star 1. 3- Button 2 will sync the scope to the star 1 coordinates and then slew to the coordinates of star 2 4- Move the scope manually till it is pointing at star 2. 5- Button 3 will read the scopes postion, compute the observation error and then compute the mounting error. 6- Now to continue you hit the "Swap star" key. Since you are near star 2 it makes sense to treat that a the star 1 now on this interation. Then go to step 2 above.
tips:
- In TestMode you can work in Hour Angle instead of Right Acension: just leave Local Sidereal Time set to 0.
- The star coordinates can be selected by Meade Star number if you have the file LX334str.ecu in the same file directory as the Palign2 program. You can get this file here: http://members.home.net/michaeljcook/ecu/ "Meade LX200 Alignment Star Catalogue (for V 3.34L firmware)"
- The "determinant" field gives you a measure of how good a choice you have made for your two stars. If they're right next to each other, the determinant will be very small. If its smaller than 0.2, you should try again. According to Ralph, "Note that you should avoid stars with similar hour angles, stars close to the celestial equator, and stars whose declinations are close to negative of each other. Each of these factors makes the determainte 0 or close to 0."