My name is Roger Hanson, and I live in eastern Washington State, in Spokane - a city of approximately 400,000 people- most of whom are fond of street and house lighting at night. The site selection was for the observatory was dictated by constraints of the double city lot we own, as well as concerns of my wife of over 30 years, Sunny, who enjoys sharing our front and side yards with two cats and a rescued dog from San Miguel Mexico (another story...) .
The future observatory was destined to occupy a small corner of our property just north of our carport, with approximately 30 degrees of overhead sky view (but heck, over the course of the year I do get to see most of the northern constellations). Prior to construction starting, A tremendously large shade Oak had to be trimmed back, and fifteen cubic yards of gravel brought in to elevate and flatten the terrain. The street below is a major arterial in Spokane, complete with some serious lighting (I am still working with that problem!) Excavation for the pier was started early on and 24 80# bags of QuickCrete were obtained. Railroad ties and concrete were used as a bulkhead above the street. In case of future grandchildren I was also told no to remove the old tree house, which was now about 5 feet closer to the ground. Interestingly, during the excavation, I dug up a dinosaur tooth.
Even my knowledge of geology and the relative "newness" of the Spokane basaltic lava flows which only date back a couple million years did nothing to disuade me from initially believing its authenticity! A trip to my dentist, Dr Ganji gave me the knowledge it was a reproduction, museum grade, of a T Rex incisor! How it got there I will never know!
The pier base was poured, using an upside down garbage c an as a mold. I had ordered a LeSeur Pier and following thier instructions I dug a massive hole in the ground approximately 5 feet below surface level and mywife helped with the task of mixing 20 bags of QuickCrete mixed with large rock for the pier base.
Using a plywood template the pier mounting bolts were embedded in the concrete and the stucture was left to set for a couple weeks while the building was framed. This was a relief, as I had twisted my knee quite badly while digging in the hole for the pier and I was hoping that if I took some time off I could let it heal- this was not to be of course and after surgery I was again motivated to work on "TheProject" My telescope had arrive previously and I had purchased a small wheeled support for the tripod. It is quite amazing how much work one has to do to set up for a night of observing. In addition the telescope took up a good portion of my garage, and I was ever the more certain that an observatory would be the right answer.
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When I had previously lived in Hawaii, I was the proud owner of a 24" StarMaster, but found that even a Dob was a cumbersome piece of equipment, not counting the worry one has during setups and take downs.
The structure was set on pier blocks, with floor joists composed of tandem pressure treated 2x8s on 16 inch centers. Yes, that was a vast overkill, but in my previous life as a Marine Corps medical officer I had been schooled in redundancy and fortification! The area between the floor joists was filled with gravel, as a vibration dampening technique. Spokane is a very dry desert like area with only 20 inches of rain a year, much of that in snow so I wasnt worried about the ground contact.
We also are blessed with 260 clear nights a year and are at an elevation of 2200 feet- though city lights are troublesome the clarity of the air is pristine. The pier base was effectively isolated from the substructure of the observatory and I could now floor the structure, which I did with pressure treated 2x6s. The resulting structure was very sound, and I found I could jump up and down on the floor joists without making any ripples in a bucket of water ontop of the pier base- something which my neighbors probably thought was quite strange. But then I am not certain anyone really understands why I am doing all of this work (surprisingly much after sunset- a good tradition for an amateur astronomer) .
Conduit was place for future wires to run thru to the pier base, and the concrete pier base was painted with red concrete sealing paint and the plywood template removed. At this point I discovered that I had not aligned the structure exactly parallel to my carport- I was only off by one half an inch in the 6 foot overlap, but that would be magnified over the course of the rolloff roof to almost 2 inches - something that would haunt me later ( I had to move all of the supports on the north side of my carport to the south by 2 inches :-(
It is things like that that make me realize how impressive the Great Pyramid is.
At that point I purchased a laser level and have found it very useful.
I calculated my power needs for the observatory, doubled it, and ran a conduit from the house underground to the observatory, to be a 60amp 220 circuit. I ran it under the floor frame and filled in the general area with gravel. I used 2x6 pressure treated flooring to deck the floor joints, and fastened them with glue and nails. I had planned on using screws- which have the advantage of easy removal if one would need to, but a rip roaring case of tennis elbow made me appreciate my Hitachi nail gun. I didnt trust it completely, so used framing glue also.
I was happy my father, who was a carpenter, didnt see how many nails I used. The floor is forever, and doesnt squeak at all.
I ran four cables for power and whatever thru the plastic conduit and then mounted the LeSeur pier. Things were really coming together. At that point my wife, who had only a passing interest in the structure up to that point, thought that if I didnt want to mount the telescope in there it would be a marvelous tea house. The name stuck.
It was exciting at that point, as a days work would really make a big difference in the structure. Framing the walls was straight forward, with 2x6s set on 16" centers. I framed 3 windows and a door, and utilized pressure treated wood thruout.
At that point I became greedy for space, and decided to increase the size of the structure on the east side by one foot, to have more room for my warm room and computer desk. I excavated, placed another set of pier blocks, and spliced into the existing structure. I ran the flooring perpendicular to the other- knowing it would soon be covered with OSB anyway- Not exactly pretty, but now you would never know. I certain my father would not have agreed- but necessity is the mother of invention.
It did not make any difference to the structural integrity and I got 16 extra inches which, in an office, is quite a bit. Next I set 20 foot 2x4s atop the entire structure, with a diagonal ripped 4x4 to support the angle iron track. IIHITDOA, I would have used a glu lam and probably 4x6, as I feel this is an area of weakness in my design. Be that as it may, to this day I have not appreciated any instability, it just seems to look a bit on the anemic side. I obtained 20" lengths of angle iron and let them "float" on the top of the sawn 4x4. This seems to work very well, though I suppose if any tornados come thru my roof could slide off, which would cause me significant consternation.
It seemed easier than constructing to the exacting requirements of steel track and caster.
My plan had always been for a roll off roof, and I felt I could build this in place. this turned out to be quite successful. I ordered 14' glu-lam beams to support the roof on the casters, and continue to be pleased with how that worked out. The casters were mounted using a section of angle iron as a template, and the entire structure was then lifted onto the angle iron. I was happy to see it would balance there and rolled freely.
I tacked the two beams together on the east and west ends, then proceeded to string rafters across- 2x8s of clear fir on 24 inch centers. I had elevated the south side of the glu lam to allow for a roof pitch of 0.5/12 which would make it appear essentially flat but keep off the water.
