Computer alignment on GE mounts?

Hi there, I'm going to be buying a new telescope soon but I'm a little
confused about the interaction between different kinds of mounts and
the GOTO computer features on the Meade & Celestron SCTs! I've had an
8" Newtonian on an equatorial mount before, but I'm very tempted by
the ease-of-use of a GOTO system.

I'm looking at buying an 8-10" SCT. Although initially it will be used
for "fun", I want to get into some more serious astrophotography at
some point. Therefore I understand that I really want an equatorial
mount - fork mounts just won't cut the mustard. But I'm also attracted
by the idea of "a quick two-star alignment and go" on the fork mounts.

I've had a look at the Celestron & Meade manuals. But the manuals seem
to suggest you can do "quick two-star alignment and go" with the
equatorially-mounted GOTO systems. How can this be? If the polar axis
isn't aligned properly it shouldn't be able to track at all?

They do stress that for "serious" astrophotography you will still have
to do a proper polar alignment, but also that you can use the
equatorial mount with a quick 2-star alignment.

Do these computerized equatorial mounts adjust in declination as well
as RA? What happens if you have the mount pointing in completely the
wrong direction, then do a 2-star alignment and tell it to take it
from there? I'm a bit confused!

I'd be particularly interested to hear from any users of the Celestron
CGE mount!

Many thanks for your helpful replies,

Phil.

P.S. I live in England, so I'll probably never get to use the thing
anyway (weather)!

"Phil Edmonds" wrote in message
om...

I've had a look at the Celestron & Meade manuals. But the manuals seem
to suggest you can do "quick two-star alignment and go" with the
equatorially-mounted GOTO systems. How can this be? If the polar axis
isn't aligned properly it shouldn't be able to track at all?

An altazimuth mount is merely a badly misaligned equatorial mount (maybe 40
degrees off the pole). The same mathematics will correct for a small
alignment error when you're in equatorial mode but inaccurately set up. The
mount tracks on both axes.

Note that the classic LX200 (non-GPS) does not do this; it has to be
perfectly polar-aligned to work well in equatorial mode.

Do these computerized equatorial mounts adjust in declination as well
as RA? What happens if you have the mount pointing in completely the
wrong direction, then do a 2-star alignment and tell it to take it
from there? I'm a bit confused!

It should work. Two star positions tell it the position of the whole
celestial sphere. It may think it's upside down and on the other side of
the earth, but it will still know where the stars are.

I'd be particularly interested to hear from any users of the Celestron
CGE mount!

Haven't tried that one -- sorry.

For more on how computerized telescopes work, see my book.


--
Clear skies,

Michael Covington -- www.covingtoninnovations.com
Author, Astrophotography for the Amateur
and (new) How to Use a Computerized Telescope

Many thanks for that Michael, that helps my understanding.

BTW, had a copy of your astrophotography book since the first edition
- must get the new version when I get my new scope. Keep up the good
work!

Cheers, Phil.