Polar Alignment

[James B]

Hi Everyone :-)

I am in the process of Polar aligning my LX200 GPS. I have got to the point where I have levelled the tripod, fork arms and the vertical alignment of the tube. The DEC scale shows my "exact" latitude with the tube vertical. Having set the telescope to the Polar home position: DEC 90° RA 0.0 with the eyepiece (rather inconveniently) under the 'scope, I have used the wedge adjustments to exactly centre Polaris in a 26mm eyepiece (erm...might have been a 40). Having done this, It occurred to me that if I rotated the tube in RA 180° (and got the eyepiece in a more convenient position) Polaris should still be in the centre of the field of view. It is not in the fov at all! I would assume therefore that the DEC was not exactly at 90° Should I adjust the DEC such that Polaris stays centred in the fov in all positions of RA before proceeding further?

I have found this instructional video for Polar Alignment: http://www.youtube.com/watch?v=zw0_O3tUhLo It seems pretty good to me but I am concerned that after setting up the tube so that it points precisely to the Celestial North, during the subsequent Autostar "one-star alignment Polaris is to be centred by using the East-West wedge adjusters. Surely this will move the scope, in PH, away from alignment with celestial north which I had assumed was the critical part of the procedure.

Finally It may be poor seeing but the region around the celestial north does not seem to contain many stars. If I can't see them, what do I do? Should I use the drift method or, as I have read synchronise on a star high in the sky, slew to Polaris and centre and rinse & repeat until both the star and Polaris centre without adjustment being necessary?

Thanks for any advice ;-)

Jim

[brantuk]

Flip the scope altitude axis over 180 and turn what is normally the azimuth axis so you can PA with the finder on top. That's the correct position for polar alignment - otherwise you'll have the finder under the scope for the whole session. If the eyepiece is upside down then all you need to do is loosen the diagonal and turn it upwards before you begin the polar alignment. Hth

[James B]

Thanks for your reply. I had a go last night and did apparently find the celestial pole: In a 40mm EP what faint stars I could see were definitely rotating around the EP axis. However, when I continued to align on Polaris the 'scope did not rotate the usual position where the EP is position at about 9 o'clock to the tube axis. Polaris and the alignment star, Capella were well out of the finder scope view. Maybe pressing "Mode" by mistake and having to get back into the align menu had something to do with it :-( I find the buttons on the Autostar very "iffy" some times.

More worryingly when at the apparent Celestial pole, Polaris was West of the CP in the direction of Alkaid and I am pretty sure the CP is, roughly, on a line between Polaris and Alkaid. So, I will start from scratch next time there is a clear sky. This is hardly Rocket Science I am surprised I am finding it so difficult!