Recent Updates (2005):
Changed current e-mail address. Added a few comments in the
Introduction on after thoughts (See below--1/3 way down).
Recent Updates (2006). Added comments about shutter getting stuck.
Recent Updates (2007). Additional comments about shutter.
(August 10, 2000): These are some of the first pictures taken of the construction of my observatory. Construction began July 25, 2000. The building will consist of three rooms: Observatory/telescope room, warm-up/work room, workshop. The building is 32 feet by 11 feet, and 8 feet in height, and its long axis is lined up with north and south to within a degree or so of north. The dome was delivered last November from Ash Mfg. and is about 10.5 feet in diameter. Completion is expected around the middle of September. Dan De Martini Construction is putting it together. Dan and his assistant, Nathan (Nate the Great), are doing all the work, but I'll be joining them to put the dome in place. I've tentatively given the observatory the name James Clerk Maxwell in honor of the great 19th century scientist for whom Maxwell equations are named, which united the concepts of electromagnetism, and showed that light is an electromagnetic wave.
The observatory is located in Nevada City, CA about 60 miles NE of Sacramento at an elevation of 2700 feet in the Sierra (mountain) foothills.
Lanphier Shutter--A Unique Design
A very unusual feature of this observatory and specifically the dome is that the dome is completely enclosed. The telescope looks through a window about 36 by 40 inches. The design is called a Lanphier shutter, and I believe is unique to Ash Dome. The dome aperture, shutter area, is composed of three parts: Lanphier window, wind screen, and main shutter. Photos shown later provide a view of these components. The wind screen is below the window, and as the shutter mechanism rises, the window rises with the accordian like wind screen pulled up from below. The wind screen is contained in a box along the skirt of the dome. A conventional (main) shutter is above the window, and rolls upward and over the top of the dome. If desired the window, can be left above the skirt, and detached from the main shutter. When the shutter is moved (by the shutter motor), the area above the window becomes open to the night sky like a conventional dome.
(August 31, 2000)
There were many interesting areas of design in building this
I'll mention a few that gave me slightly more grey hair. Some required
adjustments as the building took place.
The roof of the observatory ended up being a little more costly than I thought. Note in the photos the tin flashing in the four corners of the roof. This was a very good way to seal the area between the dome skirt and the roof outside it. I had imagined we were going to do this in some sort of conventional way using shingles, but it became apparent that flashing would be the best way. That probably doubled the cost of the domed area flat roof by putting the four corner areas in place.
The stairway into the observatory took a lot of head scratching. Initially, to give more floor space, it looked like a ladder entry would be best. After building got under way, it looked like a stairway might be smarter. That's what we finally did. Although the photos below show some of the stairway construction, eventually a trap door will fill the stair area, so that once one is on the observatory floor, there is little chance of falling down the stair way. This is a very knotty problem, because of the dome size, but I think we arrived at a good solution.
It was not apparent from the dome that the Lanphier wind screen box, which protrudes from the dome skirt, would be so big. Further, it was not realized that when the main shutter was rolled over the dome to expose the zenith that the main shutter would go below the skirt on the backside of the dome. Since the roof line of the work room was close to the observatory room, eventually it was discovered that the dome would not rotate without hitting the roof. A possible solution was to jack up the roof three inches or modify the roof line. After much discussion, we decided a section of the roof had to go. We cut out a section 15 inches from the skirt, 30 inches wide, and 3 inches deep. Flashing is used to fill the area. Fortunately, we managed not to not disturb the integrity of the roof supports. In retrospect, this worked well, since I was getting concerned that the observatory dome was getting a little high, or, looking at it slightly differently, the observatory floor might be too low.
One event particularly stands out while constructing the observatory that I think is worthwhile commenting on. A wooden form was constructed for the large footing and pier. The footing is a cube of cement approximately 3.5 feet on a side, and the concrete pier is 2 feet on a side and rises 4 feet above the footing. Some pretty good sized nails were used to hold the box in place during the pouring of the concrete (from a cement truck), but nevertheless a 'blowout' occurred in two places. One was near the bottom of the footing and one was in the cement pier. We managed to pretty well control it, but did have to grab some emergency sacks of cement I had in the garage to account for some of the loss. The lesson learned from this is to really shore up the sides with supports and probably use screws, if possible. With a little less luck we could have been repouring the whole footing and pier.
At present the observatory will be equipped with a Meade LX-200 8"
SBIG ST-7E, and various computer stuff.
Recent events in dealing with the pedestal and placement of the pedestal and telescope in the center of the dome are worth commenting upon.
(9/9/2000) I'm using a pedestal design provided by Maurice Gavin from his web page. See Credits below. As of this writing the pedestal is built and only polar alignment remains. I had the pedestal built by my contractor who has ready access to a welding unit. While this has gone well, I think it would behove anyone attempting to do something similar is to realize the limitations for welding in providing holes to anchor the pedestal. It's certainly a convenient way to provide the holes, but it's not possible to make accurate and pretty looking holes. If this is of concern, I'd suggest laying out the plate pattern and taking it to a shop where a milling machine could be used to make the necessary elongated channels. It's also important to provide long enough curved arcs for the channel to produce about a 15 degree rotation. Even if you use a welding approach to produce the base plate's channels, it is wise to produce a template for the cutting.
Regarding the centering of the telescope, one should have reasonable assurance that the point at which the two rotational axes intersect is close to the center of the dome. I'll elaborate on this with a photo for the LX-200 at a later date. It's really important to note and understand that it is not necessarily true that the pedestal marks the center line of the dome. (more elaboration later). In fact, putting the center of the scope in the center may not be a good idea, since the height of the pedestal may be uncomforably high. The exact center height may seem attractive since generally it allows the scope to be pointed at the horizon. Unless you have unusual requirements, it's probably not necessary to see along the horizon because of, for one, atmospheric turbulence. In fact, my pedestal's height is adjusted to allow the scope to see about 10 degrees above the horizon. This certainly has the desireable effect of putting the eyepiece at a comfortable observing height for me (I'm 5' 10").
I'd strongly advise making at least a 2-d wooden model of the pedestal and even some sort approximation to the scope to get a feel for how the pedestal will be placed. In fact, I'd suggest using wooden models to understand limitations and constraints where some construction problem might seem unusual. When you start commiting to metal cuts, it's not always easy to make casual adjustements to recover from errors.
Well, I'll add more to this tale later. It certainly has been interesting. I'll be back at a later date with some comments about construction and design considerations.
Sources I used for 'serious' thinking and work concerning the design of my observatory below. Also see my other web page (Amateur Astronomy) for a list of possible sources for observatory designs and information.
Owners of Ash/Lanphier Domes (obtained by scouring the net over many months)
After Thoughts (November
The observatory has functioned well in the 5 years since it was
built, as has the dome. However, I probably would not invest in
a Lanphier shutter again. I did discover within about 3 months of
its operation that any serious (photographic or scientific observing)
would be limited by looking through the pane glass. It would take a
substantial cost to install an optically flat glass in its place. This
still bears some scrutiny, but I only use the shutter on cold nights
when giving casual sky shows to guests, friends and neighbors.
I had an interesting rain leak in the roof of the domed section.
It took me a long time to figure it out. The flat roof flashing
is divided into four sections and each section is bound to the other by
a vertical seam. A vertical wall about 3/4" is on one side of a seam,
and on the adjacent section is another vertical wall that is bent in an
upside down U-shape to cover the other vertical wall. When it's very
rainy with a strong horizontal wind, rain hits the wall on one side and
goes over the top of the wall, and is guided down by the U into the
crack between the two walls. The contractors did not seal the joint
adequately to prevent a leak. It was easily fixed once discovered.
A year after the observatory was built I found an alternative
design that might be worth considering to lessen any atmospheric heat
distortion around the shutter from heat rising from the ground.
Simply raise the observatory room another 10 feet. This would get the
bottom of the shutter even further away from any ground currents caused
by heating. This was a suggestion I read, but personally never
experienced the problem, nor tried to determine if it was a problem.
When the local college built a similar observatory, I suggested this to
them. Apparently, they decided it was a worthy design consideration.
Their observatory is quite similar in size to mine, but the dome is in
the center, and 10' higher than the two side rooms. Of course, one
needs to climb a ladder or stairs, but that may be tolerable. It also
has the advantage of making the entry into the observatory room easier,
since with a short stairs like mine uses up a good bit of floor space,
about 1/7th. The college has not gone operational with their
observatory, so I have no comments from them on their design.
As of 2005 my 8" was replaced with a Paramount ME mount and a 14"
Meade OTA.) In 2004, I temporarily had a borrowed C-11 on the ME for
about 10 months. Three years ago I added some radio astronomy equipment
for listening to the sun and Jupiter, a receiver inside and dual dipole
antenna array outside. Two years ago added a an allsky meteor camera on
a 10' pole about 30' away from the observatory.
Comments (April 22, 2006)
The shutter failed to close the other night. The motor just hummed whether I tried to open it further or tried to close it. With the help of a neighbor, I got the shutter down by climbing a ladder when I could reach under the shutter cover, and grab the coupler inside. The coupler is about the size of a large can of pears, and can be rotated by hand to move the shutter. Just wrap your fingers around it, and turn. It helps to have someone take the force off the shutter. Take care in doing this. The problem was likely a motor failure. I replaced it for $320. More on this later.
Comments (July 25, 2007)
Back in May or April of this year the shutter got to be quite rough and noisy when raising or lower it. Eventually I discovered it badly needed lubrication on the cogged rail. I'll come back to this in a few weeks with more detail, and on the April entry above. I hadn't updated this page for over a year. I'm in the process of doing so now, but just wanted to get this on my new web site.
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Here is a picture I took of one such dome.
That's an 8" Celestron telescope inside. Several of these were mounted on the roof of varying diameters. I do not know a lot of details on this acrylic dome or its use, but it is manufactured by Edmund Industrial Optics. Their 16" diameter dome sells for about $85.00. I believe they make them to 36" in diameter. If not, then another manufacturer, in Alberta Canada, makes them to 60" in diameter. They may be contacted at:
or by e-mail at firstname.lastname@example.org. The cost of the 60" dome is about 300 or so U.S. dollars (I had previously guessed several thousand, but on about 4/16/2001 I received an estimate from the MAC Plastics that showed the cost was much less than expected..) Of course, transportation costs need to be determined.
Unfortunately, my trip at the PFRR was short and fairly hurried, so I did not get a lot of time to inquire further about these domes. I do not know what the equipment in them is used for, but I suspect it most cases it is for tracking rocket launches. I do not know the optical quality of the acrylic material, but it certainly seems sufficient for their use at PFRR. I am making further inquiries about this topic, and will eventually publish what I find here.
(4/18/2001) As expected, the observatory domes on the roof of the science center are used for aurora work. Pretty sophisticated observations are made, and from a few e-mail exchanges on the subject, the acrylic material offers no difficulty with their scientific observations. I'm gathering more information on this.
Another design, but for which I do not have a picture, is a very clever alternative to the Lanphier shutter. One of hosts on the trip allowed me into a conventional metal domed observatory on the roof of the center. I was surprised to find a roll back shutter with a curved acrylic window attached to the inside of the dome. If the shutter was raised, the devices would peer through the acrylic material enclosing the open shutter area. Unlike the Lanphier shutter, the window was fixed in place. I liked the idea. Unfortunately, the host could not tell me much about it and we were inside a darkened dome with little light even though it was day time. I am trying to get a picture of it. It was so dark inside the dome, I could barely make out the equipment. It may have been used for tracking purposes. The design is certainly something to consider for enclosing a dome for observing in cold weather.
(4/18/2001) E-mail contact on the use of the dome mentioned in Design 2 indicates that the dome also houses very sophisticated equipment of many types for auroral work. So far communications do not suggest any difficulty with observing through the acrylic material covering the shutter.
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No, the hole below was not created by a meteorite. It was dug by a Back-Hoe. Our ground is way too hard to attempt to dig it by hand.
Left: Hole for telescope pier footing (3.5 ft
Right: Form for footing and pier
In the photo below, that's the back of our house in the
Left: Staking out the
Right: Pier and footing poured-several tons of concrete
Remind you of anything in the photo below? Maybe the movie 2001?
the tractor on the right which was used for grading and digging.
Slab for the building with pier and footing at the south end.
Left: The walls begin to go up Right: Completely walled
The room in the left photo below is where the dome will be placed. There's a raised four foot floor in the room. We had to open up the crate of dome parts to see how this is all going to fit together with the frame. We had some interesting decisions to make about getting a stairway/ladder from the middle room into the observatory room. Despite carefully considering all this beforehand, things look differently when one is confronted reality. My wife, Jim (neighbor and amateur astronomer), the builder (Dan) and I had some long discussions about access and safety. More later.
Left: More walls and interior Right: Observatory dome parts
As a note of interest, Ash built and assembled the dome at their factory. It was then disassembled and sent. It looks like they did a very good job of assembling this into a gigantic kit. After some more interior work, we'll (I'm included on this) start assembling the dome. The big piece is part of the shutter. This looks like fun to me.
Right: Track for wheels and skirt (back towards house)
Left: Steps leading to the observing room Right: Looking south towards observing room
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