Quote:
Originally Posted by Auster1b
If I was to place the pier central, would the 275mm offset plate mounted on top introduce a physical obstacle to observing with the Meade?
If I was to place the pier 275mm North, would an offset plate to the south then be an issue with the mount/counterweight shaft or more likely the scope on an Eq mount ?
The Sirius 3.5m should give us enough room to swing a cat, so clearance should not be an issue, but how does this offset or lack of it affect dome slot alignment (the 1000mm slot opens 400mm past zenith). Could this create an unresolvable alignment ?
Thanks for your advice, Neil.
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Hi Neil,
When I had the 8" Meade LX90 wedged on my pier, I recall there being some fairly awkward / neck-straining observing positions when viewing objects high in the South. I had to get up very 'close and personal' to the pier. I imagine that with your proposed set-up, the geometry would be the same, so I definitely would not want the mount off-set to the North of the pier, as would be the case with your 'central pier' option.
Your other option, ie to offset a future GEM back to the dome centre (from an offset North pier) is what I considered - albeit briefly - when swapping over to an equatorial mount. As you may have read, my pier is offset about 250 mm North of centre, and in hindsight, it would have been better to locate my pier centrally, but I designed it for the equipment of the day without much appreciation of GEMs. For purely aesthetic reasons, I would not offset a mount on a pier, and if you're going to be doing any visual observing, I suspect that it would be much better to have the mount line-up with the pier. The other reason I did not pursue the offset GEM was that I have a tall concrete pier and I did not want it to be in tension - ie. I wanted all the weight straight down on the pier. I don't believe that the counterweights or shaft would be an issue, as they're usually angled down to the South.
Given that you've got a 1000 mm slot aperture, you would be about 300 mm better off than I am (also with a 14" SCT), and as I also said previously, I can always find a dome position to get a clear view, but slaving the dome to the mount is going to be a challenge.
Hope that that helps a bit.
Chris