Best way to do 3 star alignment
Posted 05 December 2012 - 09:34 AM
1. Initialize the hand controller, and enter time/date
2. The hand controller tells me Polaris HA clock (for example: 07:45)
3. I look through the polar scope, and attempt to place Polaris as 07:45 on the big circle. Its hard to point exactly as 07:45 but I try my best on the circle.
Then i do first star find. and its way off.
What wrong did i do?
Posted 05 December 2012 - 09:43 AM
Set up the mount, rotated in RA until the circle on the polar reticle wherer Polaris goes is on the bottom.
Adjust the RA setting circle until it reads 0 and lock it down. Don't move the mount in RA, just adjust the setting circle.
Get the LST time from the HC as you have been doing.
Rotate the mount in RA until 7:45 (or whatever) is under the pointer on the RA circle (use the circle's upper scale). Lock the mount down in RA.
Use the altitude and azimuth adjusters to put Polaris in the little circle.
Posted 07 December 2012 - 10:12 AM
When starting the sky alignment, the first alignment star is frequently off by a large amount. This is usually caused by errors in the home position of the mount. It's easy to have a 5-10 degree error in your home position. I fix this by loosening the clutches and doing a push-to alignment to the (first) alignment star after the GOTO has pointed the scope to where the mount thinks the target should be. Lock the clutches then don't loosen them again for the rest of the two or three star alignment procedure. When I align my mount this way, the second (and third) alignment stars are very rarely outside the FOV of my 25mm eyepiece and are always in the FOV of my finder. Cone errors at the attachment point between the scope and the mount will also cause alignment errors when doing a sky alignment. A three star alignment goes a long way towards compensating for this problem.
Levelling the tripod before attaching the mount will help your alignment. I use a small torpedo level because it's more accurate than a bubble one on the tripod. Accurate location and time settings will also help.