Theatre Hipparchus

Adventures with a used GM 8

For me, one great aspect of amateur astronomy is that in order to enjoy the pastime to the fullest, several other disciplines would have to be learned.  Compose website, build an observatory, understand electricity, comprehend optical systems, wrap your head around image processing and rebuild expensive machinery all came along with the pursuit.

Here is a look at the process I applied after purchasing a used Losmandy GM 8.

First have a look at the steppers. 

I found taking the motors off to be fairly straightforward.  Once you have the motor detached from the mount it is easier to continue on your workbench.

Once the cover is off you can examine the gears - in this case there was a terrific build up of sludge. I took the gears out and with spray solvent and a scrub with an old toothbrush, cleaned up the interior. I reapplied a light coating of Lithium grease.  Good as new.

Reassembly was simply the reverse of taking the motors off.

The unit tracks beautifully but I would like to have Goto, computer control  and  a host of other capabilities with this platform ergo the Gemini System. Below: the link to the  Gemini retrofit instructions. 

http://www.losmandy.com/pdf/servo-mounting-instructions.pdf

After following the instructions we were set to go. Not difficult if you go slow and methodically.

Outfitted with the Gemini system and the polar alignment scope, you now have an excellent portable mount. I have been using a 24 pound guiding set up.

Excellent for star parties or a quick grab and go. The mount is not overly heavy and does contract nicely for carting short distances. I normally remove scope and counterweights but keep the mount head attached. Unlike the Meade tripods there is no center bolt to remove to collapse the tripod legs.

One drawback of the design is the exposure to the motors. I generally take my time during installation and breakdown so this hasn't been an issue. These motors are interchangable with both the G 11 and the Titan. Also mentioned is the bottom of the tripod legs are open to collect clumps of grass. I use $4 worth of furniture coasters and small paving stones to provide a level platform in the field.

Otherwise I think it is an elegant piece of equipment to look at.

Tracks well though I have not done a PEC run with it yet.

M20 using the setup above at Starfest 2005 Mount Forest Ontario.  

Please feel free to add comments or questions below.

David