Dome #1 nearing completion in July of 2006.
The first dome, the northern of the pair, which I refer to as the North Dome, was built in the summer of 2006. I designed and built the building myself, though the shape of the “dome” is most definitely inspired by the WIYN Observatory on Kitt Peak, in Arizona. The dome itself is comprised entirely from two different flat surface shapes. There are five squares and four equilateral triangles. Two of the square sections comprise the dome’s “slot”, the upper part of which is hinged and swings up and back to open. The lower portion is easily removed and set aside while observing. The “skin” of the dome is 1/2-inch plywood, and the “ribs” which surround each part are made from 1×4 pine boards. Once assembled, the outer surface of the dome was painted and calked. After a few years of contending with very small leaks I covered the entire dome with aluminum sheet. The dome rolls on eight 3-inch casters which ride on a 1-inch thick 3-inch wide plywood ring attached to the lower walls. There are four retaining wheels set to ride horizontally on a thin band of aluminum that is attached to the inner surface of the plywood ring or track. The dome sits on top of an 8-foot octagon built of 2x4s and covered with T11 exterior siding. It is a very strong structure and has withstood several hurricanes and some nicely violent thunder storms as well as several feet of snow with absolutely no problems.
Dome sections just before assembly
Detail of the wheels, track, and retaining wheels
One thing that is a bit different with this observatory than most is that I intentionally kept it fairly open to the elements. While no snow or rain can get in I made no attempt to seal it against air movement. The floor is made like a standard outdoor deck and has 1/4-inch gaps between the deck boards that allow air to enter from below. The outer walls do not run all the way to the ground so air is able to get in under the floor, and then is pulled up through the floor into the observatory, eventually exiting at the top of the dome through gaps around the upper slot door. This ventilation helps to keep the building cooler in the summer, which is important given it can be well over 100 degrees on a sunny summer day. If I’d thought a bit more I’d have put some sort of screen material under the floor as I do get a fair number of crickets!
A recent picture of the North Dome, showing it’s new aluminum surface.
Instrumentation
The telescope in the North Dome is a 16-inch f/10 Meade LX200 ACF on an Astro-Physics 1200GTO computer-driven equatorial mount. The primary science instrument used on this telescope is a Santa Barbara Instrument Group (SBIG) ST8xme CCD camera. The camera includes an automated 5-position filter wheel containing clear and V,B,R, and I photometric filters. Also available is an SBIG ST9xe camera which is useful for occasions when a faster imaging cadence is needed.
Science Projects
This telescope is most often used to monitor cataclysmic variable stars in concert with the Center for Backyard Astrophyics (or CBA), a world-wide amalgam of amateur and professional astronomers directed by Joe Patterson at Columbia University. On the rare occasions when there are no compelling cataclysmic variable targets available the telescope is used to determine the time of primary minima of eclipsing binary stars
The #2 16-inch in the North Dome. A Meade 16-inch f/10 LX200 ACF telescope on an Astro-Physics 1200GTO mount.
first off nicely done, i started biuld mine. the base i use concrete blocks for the dome two sit on. my dome is an octagon shape design. the skin is going to be 1/2 plywood and mounted on 2×4.. in going to use 1/8 x 1 1/8 flat bar for a track and 8 garage door pulley for the dome to ride on. the only thing corncerns is wieght on the dome and how to seal it
Hello Larry:
First of all, once you’re done you’ll be so happy with your decision to build an observatory. Makes it so easy not having to set up each night, and so on.
Ya – the dome does get heavy when made of wood. But as far as sealing – I’d recommend a top surface of aluminum. I also used 1/2″ plywood as the skin – the “ribs” are sandwiched 1×4 – each had to have a different angle cut so it worked easier just to cut the 1x4s and sandwich them. But I always would get small leaks at the seams. I finally bought a roll of aluminum intended for making soffits, started at the bottom and worked up, always making sure there was about a 1.5″ overlap between one piece and the next, and folded over the corners. The dome has been completely dry for four years now. As for sealing for air-flow – I actually leave it open. From the inside I can actually look over the wall past the dome to the ground. There’s no way rain can get up under it, even in huge blizzards here had absolutely no snow (despite 30″ on top of the dome). But keeping it open like that, along with an open deck-style floor, keeps good airflow and keeps it much cooler in the summer.
Mike