The Observatory

By Marc Stowbridge
I do love to tinker, and even my observatory is not immune to my attention.  I had spent quite a bit of time designing the original obs, and was very pleased to have it featured in a Sky & Telescope article about “backyard observatories you can build yourself” (Nov. 2004).  The design was a bit short, (48” high) and the lift off roof, while quite functional, seemed a bit awkward.  I have changed the roof to a more traditional roll-off style.  I also wanted to raise the walls a bit to give more head-room, and to block some neighborhood lights.  

I kept the original structure and added 18 inch additions to the bottom of the walls.  I also changed the door from the inward-opening double doors to an outward opening
single door.  The doorway is now high enough (68” by 32”) to walk through easily when the roof is closed, as compared to the rather tight duck one needed before.  The top of the door way has a cross-piece now, and one needs to be careful not to bang into it, particularly if you are over 6 feet tall, as I am.  This crosspiece provides a much stronger structure, however, as it braces the walls to either side
.  The red “rope light” I use in the interior now crosses the door frame, providing a reminder to duck.

The roof has been refinished with a elasto-roofing paint, providing a better seal.  I also changed the somewhat elaborate interior roof support with a much simpler one.  It is much easier to fabricate and lifts the roof high enough so that it can pass over the walls without lifting.  The single roller of the lift-off model was replaced by 4 casters, 2 to each side.  These casters run on a rail made from an edge-up 2X4 with a flange made of pressure-treated decking stock.  The flange runs on the inside of the rails on both sides, and keeps the wheels from falling off the 2X4.

The casters are not very strong, so when the roof is closed, they rest in slight pockets in the rail.  This lets the roof support settle down upon the wall’s top plate.  The casters only need support the lightweight roof when it is open.  When opening or closing the roof, the front casters simply bump over the indent.  It takes very little effort to move the roof.

When the roof is opened completely, the casters are stopped by blocks of wood at the end of the rails.  Attached to these blocks are pieces of ¼“ aluminum bar stock that fit through the casters and cover the wheels.  In this way the roof is effectively locked open and held down against any sudden gust of wind.  

When the roof is fully closed, it is held in place by two turnbuckles that are attached to the inside walls with an eye-bolt.  The turnbuckles have a hook that pulls down cables anchored to the roof support.  
The higher walls prevent viewing lower than 20º above the horizon, but the surrounding trees and building make that a non-issue.  I may install an alcove into at least one wall under the roof supports, as there is little room for shelving in the 7 ½ foot diameter enclosure.  I plan to have the alcove big enough to hold a computer and monitor, as well as reference material and accessories.  The alcove will also shelter it’s contents from dew.

I am quite pleased with this new model, and will likely keep it for a while.


Click on the pictures to enlarge them.


South Tamworth Observatory