2019-04-21: Rubbermaid Observatory

Post date: Apr 22, 2019 4:5:10 AM

Over the winter, I gathered parts and build components for a Rubbermaid roll-off roof observatory. This is a low-cost alternative to a dome observatory and helped to learn how I might make a more permanent building in the future. The total cost of the site preparation, permanent pier, Rubbermaid shed, modifications and solar power system is approximately $1950. A commercial dome would be five to ten times that cost.

It still needs several weekends of adjustments, but is now functional.

I started in June of 2018 with the central pier, and used it throughout last summer and fall. After digging below the frost line, I used steel fence posts for added stiffness and rebar in the top section. Two sections of pier forms were used to make the 12 inch diameter base and 8 inch diameter upper section. The pier is a compound column that is designed to deflect less than 0.5 arc seconds under a 5 pound unbalanced horizontal force (due to wind). The shift in image center from a meridian flip would be less than 0.2 arc seconds.

The finished pier is intentionally decentered to add counterweight clearance.

This was may basic design concept in plan view and elevation:

For the enclosure, I selected a Rubbermaid BigMax 7 foot x 7 foot shed. I rented a U-Haul trailer to get the materials near the site, then used my lawn tractor for the final distance. The first step, and most time consuming was digging out and leveling the site. I lined the perimeter with paving stones and filled the center with several hundred pounds of sand.

Over the winter, I assembled the doors and roof in a garage and thought through the roof modifications. Building the doors and roof in a sheltered spot proved to be a good decision. In March, the weather was finally good enough to begin assembly.

Initial assembly was finished in one day.

My initial intent was to make the roof something that could be lifted off. But, I realized that would be more complicated then expected. And, a roll-off design seemed easier than I had anticipated. With help from my brother and a neighbor, we completed the modifications.

After everything was framed and attached, we made the cut around the perimeter. I added garage door weather stripping around the seam. It still needs a few weekends of adjustment, but is functional.

My next step is setup of the two panel, 200W solar power system. On an average clear day, it will generate enough power to charge my deep cycle battery for a full night of imaging.

The next stage of the build is posted here.