Hi Dave,
Thanks for the post and I hope you have been well.
Firstly, thanks to John B. for the excellent follow-up. Very much
appreciated.
Next, don't forget you can email us at any time for support at anytime
sales@wildcard-innovations.com.au
You can phone us 09:00 - 17:00 Australian Eastern Standard Time
on 02-9457-9049
There is also an Argo Navis User's Group hosted on Yahoo at -
http://groups.yahoo.com/group/argo_navis_dtc/
The reported WARP value is expressed in units of degrees.
It is the difference between the angular separation of the two alignment
stars (as a function of time because of the apparent motion of the sky)
and the angular distance the encoders appeared to move based on your
ALT REF setting.
As John suggests, the first thing to check is always the mechanical
aspects of the setup along with the cabling.
The angular separation of Hadar & Arcturus is about 79 degrees.
The angular separation of Rigel Kent & Spica is about 55 degrees.
When the reported WARP value was larger on the former pair,
it could simply be whatever problem you are experiencing is a function
of angular separation. In other words, the further the two stars are apart,
the more likely the difference between their real separations and what
your scope measures by way of the encoders is a larger numerical value.
You might ask, what type of problems could result in a large WARP value?
As John has noted, mechanical slipping is always the
first thing to check.
This is where a daytime encoder test is indispensible.
If the daytime encoder test gives satisfactory results, the next thing
to try is AUTO ADJUST ON (I note you have tried this).
What AUTO ADJUST ON does is assumes that the only error is the setting
of the ALT REF point. It then adjusts this point to give you a non-zero
WARP factor. For mounts largely free of fabrication errors or slippages,
this is exactly what you want to do. However if your mount has some other
problem, then the ALT REF point might become incorrectly adjusted
and will only deteriorate the pointing more.
Therefore next is to consider whether the mount has one or more geometric
fabrication errors or flexures. A quick check of your sets of alignment stars and
a guess that you were performing an alignment not long after sunset
reveals nothing obvious to me. Both pair look as if they have about roughly equal
zenith distance separations from your Victorian location at the early
post-sunset time (this is significant in terms of some mount errors which
I won't go into here in this brief response).
Do you know whether your pointing error worsens as you approach the zenith?
(Please don't use the GUIDE numbers as a estimate of pointing error, since these
have been decomposed into two axes of rotation. Instead it is better to estimate
the pointing error in terms of eypiece FOV's). Rather than reply here, it is always
better to email me at
sales@wildcard-innovations.com.au as I will tend to
spot a direct email faster than we can monitor all the forums.
Finally, one further piece of advice is that in the face of most types
of systematic errors, the pointing error will tend to be smallest in the
neighborhood of the two alignment stars. Keep in mind that you can
re-align at anytime. With this in mind, you should select one of the stars
to be in the neighborhood of the region you are about to observe in.
When you move to a new part of the sky, then simply align again.
Hope this is helpful.
Best Regards
Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au
