Re: Switching Scopes on 900GTO

Joe Zeglinski


What I was thinking about is quite straight forward. Basically, take one
misaligned OTA at a time, - perhaps one as the master reference - and do the
alignment (RECAL, etc.). Switch to the next OTA, and see how many arc seconds
(minutes), it is off from the first OTA. Write this down, so the next time you
switch to this OTA, (or switch back to the first one), you know how much to
offset your target entry. Finally do this with the third OTA, which will have
a different offset relative to the fist one (the master reference).

Next time you use any of these OTA's, you do a GOTO, and then "adjust" by
the offset (error compensation RA & DEC). Now the target should be dead

If the ASCOM driver could have this option of setting offsets for a series
of OTA's, then it would be central and automatic, every time you changed or
added new OTA's.


----- Original Message -----
From: "hewholooks" <hewholooks@...>
To: <ap-gto@...>
Sent: Friday, January 18, 2008 7:32 PM
Subject: [ap-gto] Re: Switching Scopes on 900GTO

Joe and Dean,

Thanks. I think the math is beyond me for your plan, Joe, but it
does sound like a good idea. I will check with CDC and ask about
sync vs rcal functions.


--- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...>

Hi Hunter,

On the question of aligning all your scopes, would it not be
possible to
determine the "pointing error", for each scope, without it being
aligned, and simply plug in the correction to the target
coordinates, based on
that predetermined fixed offset? It would be nice if something like
that could
be done right in a Planetarium program, so as you switch and
specify which OTA
you are using, the program compensates for you.


----- Original Message -----
From: "hewholooks" <hewholooks@...>
To: <ap-gto@...>
Sent: Friday, January 18, 2008 3:23 PM
Subject: [ap-gto] Switching Scopes on 900GTO

Sorry, but another almost owner question.

I currenly image with 3 different scopes - Orion ED80, APM/TMB
130/780, and C9.25. I place these on my mount one at a time on a
dual saddle and guide with an ST80 on the other side of the

Most likely these scopes point in slightly different directions
mounted in the saddle and probably none are exactly orthogonal. I
would plan on doing the same with the 900GTO, although I will
the mount set up in an observatory, not changing the polar
from night to night.

As I understand it, the AP mounts are dependent on orthogonality
perform accurate gotos across wide sections of the sky, so that
leave me out (unless I spend the time making each scope
orthogonal on
it's respective dovetail). If that's true, I can live with it
because I hardly ever observe and most always image, syncing on a
star nearby to my intended object and slew a few degrees from
to the object.

Question is - assuming I am not totally skewed in my
will this work out for me? - that is - syncing close to my subject
and expecting the mount to get me close enough to be within a FOV
the target.

Second question is - after I image one target and want to go to
another that night, should I sync on a star near the new object
proceed in the same fashion that I did with the first object, or
do I
need to turn off the mount and start over so as not to corrupt my
planetarium alignment with another sync?

Third - when the session is over, should I turn off the mount as
if I
were taking down a temporary setup for the night in anticipation
using another OTA the next session, or should I park the mount

Thanks in advance.


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