Back in the observatory

by Robert Buehler

Just after Christmas of last year, I made the decision to get involved again in astronomy and astrophotography. The observatory had been completed in 2013 but circumstances beyond my control prevented me from being away from the house in the evenings, and of course, that’s when the stars come out.

Right away, I made a couple of discoveries about the observatory. One, I had built it too small. I should have made it three to four feet larger in all directions, but made a decision at the time based on economics. I have a Takahashi TOA130 refractor with a long imaging train attached (camera, filter wheel, focuser, field flattener, and rotator) that makes the scope tail-heavy, and requires that everything be pushed forward in order to balance. That, in turn, pushes the nose of the telescope uncomfortably close to the north wall when it slews. It clears, but with only a couple of inches to spare.

Two, the roll-off roof is heavy. When we built it, I used eight 2x5 inch polyurethane V-groove wheels (from McMaster Carr) that ride on inverted angle aluminum. Cost per wheel was about $31. The polyurethane wheels have a fair amount of friction as they ride over the angle aluminum. I should have used stainless steel V-groove wheels (cost: $216 per wheel). I may still end up replacing the current wheels, which would require jacking up the roof to gain access and likely would not be a trivial undertaking. Opening the roof is easy because I can push on the exposed steel joists. But when the roof is entirely rolled off, as it must be for imaging, there is no easy way to get the thing moving toward the closed position. I use rope, profanity and name calling, but it’s only when the roof is exposed by about 18 inches that it becomes easy to close.

Yes, I could motorize it, and that is something I’m considering. The cost of motorizing the opening and closing of the roof would be about $2500-ish. But I think I want to look at a low-tech solution first. Today I have a hand winch being delivered from Amazon that will pull 1500 pounds. Cost, $30 or so. It should work. We’ll see.

Meantime, I am trying to imagine the observatory not as being too small, but rather cozy. Or efficient. Compact. Those words seem to make me feel better about the size of the observatory.

I still think having an observatory is way cool, and beats what I had before, hands down. At least I don’t have to deal with skunks and snakes. I’ll work out whatever problems I have with dimensions and the roof pretty quickly.

Leave a comment