From: "jimchung2338" <jim_chung@sunshine.net>
Date: May 8, 2011 9:10:22 AM MDT
To: Astro_IIDC@yahoogroups.com
Subject: Dob on a GEM
Most of you will know that I've been doing my planetary imaging with a 12" Skywatcher collapsible dob using Meade Autostar and motors to drive the alt/az dob base. The problem is that it takes constant corrections to keep the image centered as you can't rely on Autostar in alt/az mode at high focal lengths.
Since CSC was predicting very good seeing last night, I wanted to be able to monitor the seeing over two hours and capture data when the seeing peaked. Doing this with the dob mount would have been exhausting so I designed a simple oak fork mounting system to place the dob onto my EQ6 mount. Definitely a two man job lifting and maneuvering the 60lb OTA into the dovetail saddle. I needed over 55 lbs of counterweights to balance necessitating a quick visit to Sears just before closing time to get an additional 20lb free weight.
It worked well and I was able to track Saturn from 11pm to 1AM with only very minor corrections every 10-15 minutes. Unfortunately the seeing was never that good so the imaging was a bust.
http://dl.dropbox.com/u/4852049/DOBonGEM.jpg
Jim