Re: DS24 problems

[Tom Droege <tdroege2@earthlink.net>]

It is probably too much to ask for a deteriorating RA drive to be 
consistent and produce uniform cork screws images.  The problem is that the 
RA drive can introduce periodic error if it is not working correctly.  Thus 
it apparently speeds up and slows down.

At first I was suspecting wind for causing this problem.  But then it went 
away when I fixed the drive and I did not note any significant change in 
the weather when I worked on the drive.  ;^)

l think we need to be prepared to live with a not so perfect drive 
system.  Sigh!

Tom Droege

At 02:52 PM 1/18/03 +0000, you wrote:
>On Fri, 17 Jan 2003 15:24:52 -0600, Tom wrote:
>
> >This is a problem caused by a deteriorating RA drive.  I have since fixed
> >it.   I believe I mentioned this in a post here.  OK, I just looked, and I
> >mentioned "cork screw" shaped stars in the 12 Jan 2003 23:16:05
> >post.
>
>I can't find any corkscrews. Probably using a different
>viewer! My PSF fitting said that the images were consistent
>and not erratic. The stars are a bit comatic and a bit fuzzier than
>one might like. The 6 selected images on the other hand show
>clearly double images. The separation has the same position
>angle (as measured by my eyeball) but different magnitudes
>for the three pairs.
>
>The separation is definitely not E-W. I don't see how it
>happened if it was only the RA drive having problems.
>
>Another problem, for me, is how my code coped with 5 out of
>6 without setting any flags! The one I checked in detail
>appears to have processed two complete sets of stars and
>then to have chosen one of the sets for the astrometric fit
>without once getting confused ... or even noticing that it
>might get confused. While there is much to be said for
>robust code - it is, of course based on Michael Richmond's
>Match routines - this is going a bit far! Over 800 stars
>were used for the fit: over 800 close pairs were rejected
>correctly.
>
>Andrew Bennett, Avondale Vineyard