New observatory in Bourbon, Missouri
Post date: Jan 7, 2012 4:26:31 PM
A large part of the motivation to move to a 4.5 acre site near Bourbon, Missouri was to create and have my personal observatory in my back yard for convenient access. Darker skies will help, too. I am planning a roll off building to house my 14-in Celestron SCT. As it will only be used with a CCD camera attached, the building will be just big enough to cover the telescope and computer system. It will be a ongoing project that I will chronicle here as progress is made. Stay tuned.
The first challenge was to locate the observatory. I chose a spot on the South side of my equipment shed to be close to electricity and to get shaded from a dusk-to-dawn light in my neighbor's yard. There are two distant D2D lights to the South that I may persuade the owner to shield but I plan to put up a privacy fence as a safeguard. My horizon will always be higher than about 20 degrees.
The first step is to locate and build a pier to support the GEM mount for the telescope. A concrete pier is easily constructed and quite affordable. The pictures below tell the story quite well.
A hole was dug and a 12-in diameter Sonotube form was placed over it. The Sonotube was plumbed and braces installed to hold it in place.
The hole is about 18-inches deep as I don't worry much about frost heaving. I can always re-align with the pole if needed.
Four 80-lb bags of Quikcrete were hand mixed to fill the form.
The form filled and the top leveled.
The base for the GEM needs three 3/8-in studs to attach to the pier. I used 10-in lengths of threaded rod which were held in place by the plywood disks.
The threaded rods were oriented to have a "pretty close" N-S alignment. The mount is adjustable for fine alignment.
With the plywood jigs removed the pier is ready for the GEM mount.
The test fit of the telescope mount is rock-solid. The GPS in my Android phone gives the location as
+38 deg 08.045 min
-91 deg 16.178 min
+/- 13 ft
Elev 1000 ft
The next steps involve building a track system to allow the telescope shelter to move off and expose the telescope to the entire sky.
Two rails are used, each consisting of two 2x4s on edge. Chamfers were cut so that a V-shaped groove could center a 1/2" PVC pipe. A total of 16 feet was chosen for the rails.
The rails were mounted on 4x4 posts (2 ft long) that were sunk into the ground.
Dry mix concrete was used to set the posts. No need to mix with water, soil moisture will soon cause the cement to set.
The rail system is complete (still missing the PVC pipe, though). A floor has been added. The size of the floor is 3 ft x 4 ft - ample to store the 14-inch telescope.
The next step is to build the movable superstructure.
A simple 2x4 frame was built. Note the grooved casters (from Grainger) and the PVC pipes on which they roll.
The almost-finished shelter. It rolls off to the East but does not obscure the Eastern horizon any more than that distant tree line (about 25 deg). Sheet siding and a corrugated plastic roofing called Ondura provide the outer covering.
The telescope is a tight, but comfortable, fit inside the shelter (here shown with the gas grill cover used a supplemental protection.
The, more-or-less, completed observatory
Note the grass and rock that has replaced the mud from the previous images! Much more pleasant. Note the computer beneath the "table" that serves as a dew protector for the computer and other electronics. The computer is accessed via wi-fi by another computer in the house - no more frozen feet nor mosquito bites! Data acquisition on an extensive list of variable stars is scripted with several hundred measurements possible on a clear night.