[APML] Mount Flexure [was: Ticket to Chile]

[Matt BenDaniel <matt@starmatt.com>]

At 10:02 AM 5/9/2002, Chris1011@aol.com wrote:
>In a message dated 5/8/2002 10:44:48 PM Central Daylight Time, 
>matt@starmatt.com writes:
>>
>>Sorry there's some field rotation and/or flexure evident. I was guiding 
>>on IC4628 at the time, so you can see that flexure was at least partly 
>>responsible.

http://world.std.com/~mattb/gallery/astro/cmw.html

>Very nice Milky Way.

Roland, Thanks.

>That looks like pure field rotation to me. "Flexure" or better yet 
>differential flexure, would have affected all stars equally.

Most of the trailing is perpendicular to a point significantly south of the 
guide star. I think that the piggyback mount (a Losmandy DCM-2) twisted 
around a line that passed outside of field on the right side.

The DCM-2 uses a rubber sheet at one of its joints. It also has mating 
surfaces which are covered by slippery black paint. To prevent flexure, I 
tighten its large screws with large torquing force. Those forces in turn 
can de-align the mount.

I'm modifying the DCM-2 now. I think exposed aluminum (possibly even 
knurled) surfaces will keep it from flexing, and the user (me) will not 
have to crank the knobs so hard.
--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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