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A main telescope is basic for all astronomical research. The observatory will include the housing, rotatable dome, astronomical mount, and a state of the art reflecting telescope system.
(Note: Telescope system schematic to be placed here in the future)
Major components of the system include:
These facilities will support the following programs:
Once we were assured we would get the two Boeing mirrors, I decided to build the grinding and polishing machine which I had already designed. This was necessary as hard grinding, polishing and finishing large, heavy mirrors to wide field tolerances would have required tens of man-years of effort.
Russ Trask furnished all of the steel for the machine. Butch Bretsen did all of the welding. It has a high speed diamond spherical grinding unit which has reciprocating arms and ball drive for both ceramic and pitch laps adjustable for stroke length and position of lap on the mirror. The table under the mirror rotates in either direction. The entire mirror platen is tiltable on giant bearings to make possible Foucault and Ronchi testing. Positioning of the upper head up and down is accomplished by a 4" diameter Acme threaded main column with a small two-way gear motor. The unit is large enough to do the 40.5" mirror. As a preliminary practice exercise I spherically ground and polished my own 22.5" Pyrex mirror with very good results. The system has performed its job superbly for BPAA's 27.5" mirror, shortening the mirror preparation cycle to one man-year from between 15 man-years to infinity.
It can now be used for the 40.5" mirror, and also to quickly prepare 6" - 16" mirror blanks -- ready for final lapping and finishing -- in minutes as compared to man-months necessary by the time-tested hand grinding method.
We decided to use the 27.5" zerodur mirror rather than the 40.5" mirror in the Battle Point Observatory in order to limit the size of the dome to conform with the building height restrictions. This mirror was designed for sensor calibrations and could not be used, as was, for astronomical observation.
The grinding and polishing took approximately one year. First, about 0.5" in depth was spherically diamond ground from its surface to eliminate existing ball depressions. Then ceramic laps were used in four stages of grit to smooth the spherical surface. An 18" spherometer was used to extremely accurately monitor both sphericity and focal length. After sphericalization with 8 micron garnet, pre-pitch laps were made using the mirror as a molding agent and final spherical polishing was begun on the mirror.
After almost perfect spherical polishing was completed, parabolization or figuring was begun by deepening the center of the mirror 0.00045". This was done totally with a smaller pitch lap. Both Ronchi and Foucault testing was used to monitor the figure. The final tests were completed by Foucault technique using zonal masks with Bob Mathews' help in the reading and analyses.
A 4" outer diameter tubular hole was ground leaving a 3.5" diameter plug. This plug was left in, surrounded by plaster during the entire grinding and polishing operation. After completion of the mirror, this plug was removed by grinding a tiny amount of holding glass out from its backside with diamond cutters furnished by Molly Griest.
The mirror was then carefully crated and taken to California by the Gardiners to be vapor deposit alumized and "enhanced". As of February, 1997 it is still in the crate ready to be mounted.
The telescope base and the drum and fork were built during this same period. Quarter inch steel plate donated by Russ Trask was used in its construction and it was flame cut by Johnnie Magnuson. Most of the extensive welding was done by Butch Bretsen. All of the columns, including the central fork column are very heavy steel. Precision bearing surfaces were machined into the columns before welding. Huge Timkin tapered bearings were used on the main fork column with a take-up nut at the bottom of the column. An internal conduit was placed inside the structure and pre-wired for eventual control wiring. The three major base units, which includes the base, the drum and the fork, weigh more than 1000 pounds. The base has mounting feet which match the bolts in the concrete pad at the Battle Point Park Observatory.
Gears were made - one of 28" diameter with 360 teeth and one of 14" diameter with 180 teeth for the polar and declination axes. The two main gear blanks, from Alaska Copper and Bronze, were accurately jet-cut by Micro Jet of Monroe. Indexing plates were first made on the milling machine using a precision rotary table, one with 360 holes, one with 180 holes, to control the spacing of the gear teeth. I then machined these, including the worms, using #12 pitch teeth.
The telescope tube, the final unit in our telescope, was made by rolling 1/8" aluminum plate into a cylander about 30" in diameter and 36" long. Both side yoke bearings were fit and bolted into this unit. A 5/8" back plate was welded to the back of this unit with 16 threaded mounting holes. This unit is precision-matched to the cell which holds the mirror. This cell consists of two discs of 5/8" aluminum. One is bonded to the mirror with nylon spacers and silicone. The other one is mounted to the telescope tube, and the two of them are interlocked with four special mirror adjustment units. This cell weighs about 100 pounds and the mirror weighs about 200 pounds. In addition, there are 18" diameter 1/2" thick steel counterbalance discs which bolt to the back of the cell. The front of the tube is composed of one 1/8" aluminum tube truss member bolted to concentric rings. The outside ring fastens to this assembly and can be rotated on nylon rollers. This outer ring contains the spider, the diagonal flat or the Cassegrain secondary mirror and the mounting provision for the viewing instrument group. To place a CCD at the prime focus another spider is inserted into the main tube.
Both right ascension and declination structures are oriented with #34 series stepping motors. Provisions are made in each to adjust the spring load of the worms against their gear wheels. These stepping motors are controlled by a Sky Probe 1000 and a 486 computer. This allows the scope to find 13,000 stars, planets, sun, moon, nebulae, etc. and to track each at its approximate tracking speed. One hundred sixty reference stars, any two of which can be seen, set the reference for this unit and this reference is memorized even with the unit shut off. A second reference system containing reference stars within any 1 degree-minute of arc viewing angle, will use CD ROM's available from the Palomar Optical Survey System (POSS) to provide reference star fields for distant dim celestial objects.
This control unit automatically senses backlash in the gear system and corrects for it and also automatically corrects for near-earth refraction. The hand control controls right ascension in two directions and declination in two directions at speed controlled by the slew button.
The entire construction is finished and tested ready for assembly. It will be dismantled in three pieces, crated, and taken to the observatory where it will be lifted by crane to the rooftop.
This won't be until the dome is finished which gives it protection from the weather. The dome will be powered by two gear reduction motors and spring loaded rollers. They are actuated by movement laterally of the scope itself. This movement is detected by the use of infrared light and the scope and infrared detectors on each side of the opening of the dome.
I have received a proposal for BPAA to perhaps acquire a one-half acre piece of land near Table Mountain in eastern Washington. I would consider making the 40.5" catadioptric with an F2 focal length, a front correction plate and hyperbolic secondary. We could grind and polish the 40.5" Boeing mirror, build an appropriate telescope mount and erect it inside a domed observatory at this distant site to be totally remotely operated by Internet from our own observatory here on Bainbridge Island. Perhaps we could collaborate with another astronomical group in the vacinity of the new site so they could help us maintain the new observatory in turn for their remote use of our BPAA system. This site might possibly be the Goldendale Observatory which already has an operating crew.
We have professional facilities, trained telescope makers, and a school system eager to provide young, dedicated and intelligent students who would be given the chance to work on interesting precision equipment, leading to exciting research and discoveries.
What are possible projects and research that can be carried out with the use of a telescope of these capabilities? The observatory:
Basic Research Program (Typical example, using major elements of the telescope system)
Assume the following:
Section I.A: Purpose and Charter
Section I.B: History and Chronological
Development
Section I.C: History of Battle Point
Park
Section II.A: Facilities: Physical
Plant
Section II.B: Facilities: Operating
System and Equipment
Section II.B: Facilities: Operating
System and Equipment, part 2
Section III.A: Organization and
Administration
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