My Mini Dome Observatory

Our introduction to Star Hopping began in 1996 at a Thanksgiving get-together, upstate near beautiful Bear Mountains. Prior to setting off for the hills, I prepared myself at the local lending library, by leaving with a sizable carry-all filled with a variety of monthly periodicals. I was intent this time on having enough reading matter to keep me pre-occupied. A single issue, amongst all the magazines had dominated our attention. It was about amateur and professional astronomy, Hubble space telescope results and theoretical updates in astronomy. Up to that moment our interest in optics, had been limited to 35mm nature photography and occasionally some bird watching. I wasn't contemplating adding other interests, to an already lengthy list, but the impact of the Sky and Telescope periodical was overwhelming.

It was an interesting coincidence that the subject of building a dome came up while I was considering retirement. But the blame still goes to Sky and Telescope and the unknown culprit at the library who slipped the solitary November issue into our weekend magazine reading.

Dome

Soon after returning from the Thanksgiving holiday, I began to prepare winterizing chores on our flat roof that needed attending-to. It was a convenient opportunity to decide on a location, where I might position a dome. I also wanted to bring up my first impetuous acquisition, a 90mm Maksutov spotting telescope, which had never gotten it's first trial. Just before sundown, I began to set up a tripod, but unexpectedly, it had gotten very windy, and the temperature dropped rapidly. I had to retreat from the rooftop, but found cover within the roof access hatchway, just a few steps down the ladder. This simple occurrence was providential. It forced a quick, sensible decision to take full advantage of the access hatchway. With protection afforded by wearing layers of warm sweaters, a pair of hunters break-open mittens, and a low rotate able dome, I should be able to enjoy hours of star exploration on clear, relatively good, seeing nights.

ACCESS

For many unexpected reasons, the roof access was worth taking advantage of. The width of the trap opening had to face Polaris, and fortunately It did. The initial intent was to have the observer seated partly below the roof level, which simplified the design. A low profile dome design takes advantage of the roof buttress ability, to buffer and deflect the wind from three directions. The interference from some street lamps, that are level with the roof, can be easily blocked, by lashing down horizontal swinging blinds, that give no resistance to heavy winds. Lastly, the roof can still be reached for occasional upkeep through the dome.

For the initial planning, I created a mock setup to get a better visual grasp of the available space. An assembled LX-10 was placed on a desk, to make the process of visualization more graphic. I would often take free moments to sit at the mock-up, and mentally draft ideas. My focus was on making the dome functional, and one hundred percent storm-proof.

sitting

A template of masking tape, applied to the desk top, surrounding the telescope, represented the inside dimensions of the raised access hatchway. A template of cardboard, shaped like a dome cross-section, was suspended from the ceiling, and centered above the desk template below. The shorter sides of the access port, necessarily must face north-south. The only telescope mount that will function favorably in this setup, is the fork-equatorial. The rear of the fork must face south. Since the LX-10 fork mount is off-center, a working space of about two foot square remains for the stargazer to observe from.

The front of the declination-mount-wedge is swung slightly to the east or west about it's axis bolt, till it is satisfactorily locked-onto the pole near Polaris. Declination corrections are alternately made until vertical star drift is eliminated. These adjustments are made using a high power cross-hair eyepiece. The remaining bolts in the slotted openings, are then tightened to a necessarily, very rigid, supporting shelf. Don't expect the telescope tube axis, to fall centered beneath the dome! It should only lean towards center. When facing south, the scope tube must clear the dome when it is slewed through all it's positions.

Two lengths, of roughly 2 foot and 3 foot angle-iron stock (pre-drilled, and pre-tapped), are leveled, pre-calked, and secured to the outer edges of the metal-covered protruding roof-top frame. The cutout in the base of the dome-support rests on the angle-iron stock, and is bolted to the angle stock from the inside. The remaining outer space between the roof opening, and the inner drum's circumference, serves as needed perimeter shelf space for accessories. Some items, such as a small monitor for a video setup, can be swivel mounted on the inside base wall, if it doesn't interfere with the telescope.

ASTRO

When seated in this space, most of the torso is below rooftop level; the hips and knees are slightly above ceiling level. A folding, fixed, or hinged supporting platform, that can handle twice ones weight, must be constructed below the ceiling level; leaving sufficient room to enter and exit via a six foot, folding ladder. The added weight of a wood ladder is preferable and takes up little space.

I commenced to further narrow the choice of materials, after I was convinced my design was basically sound. I had fortunately decided to forgo the use of aluminum for the upper dome, and I also lucked out when I located a very responsible fiber-glass source. I had chosen three fibreglass sections to be fabricated, from two existing molds. When all the components were finally interfaced, the finished project was an attractive, unobtrusive, and very practical mini-dome; much more so, than I expected. I saved on cost and time, by being present and involved at various stages of the fiber glass fabrication; especially when careful preparations were being made for the addition of numerous threaded bushings, before the fiber glass sections were joined and/or laminated. The threaded flanged bushings made for a professional touch, not necessarily found in custom units. They were the key, to all the joining needs that had alluded my thoughts, in the early stages of planning. The embedded bushings provided the means to interface the assembled fiberglass elements to the steel guidance hoop in a single step, Secondly, they served to properly secure the dome cover, and compress the dome moisture seals. Securing the hoop to the juncture of the dome components greatly simplified the rotation design, and security as well.

I wanted a very strong and solid foundation that wouldn't be wanting for repairs in the future, The laminating procedure had to be done indoors, close to the rear exit. The drum had to be fabricated, working from the outside, inward. It was the only practical solution to maintain control of the exterior dimensions. I used a flexible plywood product, called 'Wiggle board', and bonded many layers of it, to ensure a trustworthy base. Aluminum was then bonded to the inner and outer surfaces. After the bottom rectangular cutout was made, a hard silicone rubber was applied to prevent moisture seepage.

There could have been less complexity in the waterproofing design I chose, if the domes flanged skirt had extended two inches lower, over-lapping past the upper bases perimeter. Watch for proper centering and sufficient clearance to compensate for any unexpected eccentricity when the dome and flange are rotated. A forty inch diameter welded hoop, of one inch square steel tubing, can be found in trampolines, available in large Sporting outlets for about $40. If properly engineered, this can be the rotation and locking inter-face. Use felt pads or loaded casters against the outer surface of the hoop to help keep the domes rotation from being slightly off center. The hoops are not always perfectly true. The height of the base will be determined by carefully varying, or compensating for these factors:

  1. A functional and safe platform access height.
  2. The distance between the ceiling and the roof.
  3. Setting the wedge to the correct declination position.
  4. How far back the wedge is positioned for safe telescope clearance.
  5. Interface space required for the chosen method of rotation.
  6. Limit lifting the dome from the base except for unforeseen service needs.

(There is a tendency in frigid weather, for some condensation to freeze on the under side of the dome. This depends on how much vapor is allowed to rise from the living quarters below, and also the material chosen for the dome. If the SCT is covered, it may be of minor concern. There is a 2" wide tape of sealed-surface rubber foam, which is available at refrigeration suppliers, that I had applied to the under side of the fiberglass dome to overcome condensation. The temperature should be over 60 degrees before it is applied.)

Purchase flanged 1/4 inch threaded bushings; the type where the bushing end is pressed into 5/16" holes, drilled into wood. These are essential to secure the hoop (that comes predrilled) to the bottom of the dome's inner flange. If the dome is fiberglass, the waste from the cutout is saved intact and is pre-drilled to accept the threaded bushings. The waste is sandwiched against the under side, of a considerably over sized dome cover; made from a portion of the dome mold. The bushings should be plugged with wax or clay to keep the resin from entering the threaded holes.

Two parallel rows of thick adhesive-backed rubber weather seal, are applied to the overlapping outer edge of the cover. Never attempt to remove the cover if the temperature is near freezing, the rubber could tear. On a four foot diameter dome, a minimum of eight bushings are required to tighten the aluminum, U-channel locking strips, plus four more bushings, for two extra grip knobs, plus two for securing a metal-strap handle for lifting the cover. The dome should be waxed at least two times a year. The fiber-glass surface could powder in time if continually neglected, forcing you to protect the surface later with unnecessary painting.

I decided to make use of the two lengths of pre-drilled angle-iron stock. They were fastened to the underside of the dome temporarily; in such a manner as to provide ample guidance for the dome, to keep it constantly on track, as it was being drawn, sliding-up on a magnesium ladder substitute.

All of the efforts taken in planning and preparing had payed off. The time consumed to set up the ramp, bring the base and dome into the enclosed backyard, tow the base safely topside, followed afterwards by the dome, and then to complete its installation, took a total of about two hours, plus about a half an hour more to adjust the many lift restricting locks. I did find it difficult, setting up and shimming the wedge mount to a perfect level, in the limited space. I had to remove the fork mount, bring it downstairs, and dis-assemble the fork elements. The reason was the factory had goofed, in their drilling fixture setup. I had to file two of the lower mounting holes into adjustment slots. Only then was I able to bring the scope axis to a true level which would remain true when rotated.

 Mini Dome

There were many custom improvements, and some upgrades. The most recent was creating a pneumatic wall mounted, rail-driven, fold-away observing seat that partly compensates for frequent declination shifts as I slew the skies, observing from fifteen degrees dec. to well past the zenith above. Adequate planning and effort pays back many fold, in enjoyment, and appreciation.

Follow up with your own versions to enjoy Rooftop Star gazing. There's nothing that can compare, if you are sequestered and lazy like me. Enjoy frequent, pleasant, and peaceful interluder sailing through His heavens. If it has to be shared with a few clouds now and then, be calm, most times it's only a short time before there gone.

SkyShow


Want to hear of something,
that is most likely important news to you?

CLICK on this HOMELESS E.T.,
to scan, and Bookmark....
these...choice Links, to eye-opening, documented incidents.".

These links are here to make issue of the ongoing presence of many different UFOs all over our planet.
Actual History: In 1961 a branch of our government had chosen to finally assign the salvaged technology, taken from UFO's that crashed in New Mexico back in 1947, to chosen research groups for the purpose of back-engineering, and further research and development.
The understood physics of the salvaged technology was hardly apparent, at that particular time in our technolgical development.
Col. Philip Corso(Ret.), A member of President Eisenhower's National Security Council and former head of the Foreign Technology Desk at the U.S. Army's Research and Development department, had the assignment to distribute the salvaged "Foreign Technology", as he stated in "The Day After Roswell".
At issue is: Will we ever have.. a formal rewrite... of that unwritten history.
UFOs are not a joke! They are a reality!
And.... Bell Telephone Labs did not invent the transistor, nor were the other research groups inventors of fiber optics, and the many other alleged firsts, years ago!


And perhaps now, or at another time,
you might appreciate a brief visit to an exhibit of figurative sculpture,
once a creative pastime of mine.

Curious? Then do

CLICK HERE





God Bless America






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