A Trip to Yerkes
By John Reed
On August 23, Bill Franke, Chris Lasley and myself embarked on a mad weekend dash to Rockford, Il to visit Astro-Physics, a manufacturer of excellent refracting telescopes. We met with the owner ,Roland Christan, who gave us a five star tour of the facilities. We saw mounts very similar to the one the club purchased being milled out of solid blocks of aluminum. AP makes all their own parts including the knobs! We also saw the optical shop which used to be comprised two sections: a grinding room and a polishing room. However Roland informed us that he now uses a state of the art glass milling machine which shapes the glass blanks into nearly a perfect curve using diamond wheels. He then goes from this straight to the polishing machines leaving the grit grinding room nearly unused. Finally we got to see a laser interferometer which Roland uses to test the optics he produces. Each lens has a 3-D contour map of its surface printed by this computerized machine, verifying its quality. A great tour, we all learned a lot.
We did a little business while we were there, having Roland check out Jim Hoskin’s six-inch refractor as well as Bill’s five-inch. Both are now fit and ready to produce beautiful images. We left saying good-by and thank yous to the AP bunch for showing us such a good time.
Well, believe it or not, about an hour’s drive from AP is the largest lens type telescope in the world, Yerkes observatory! Naturally the next morning found us abain on the highway bound for William’s Bay Wisconsin in order to tour this 100 year old facility. The impressive 90 foot dome rises high above the senic Wisconsin farm land and is easily visible as one approaches the small town of William’s Bay. After a short drive across the green, manicured observatory grounds, we approached the ornate, majestic building. I could feel a sense of history in this place. Some famous shoes had trod on these very steps leading to the imposing entrance. E. E. Bernard, Edwin Hubble and others had done work at this famous observatory. We entered the building and waited for the next tour.
A short flight of steps takes visitors up to the actual observatory room, housing the 40 inch refractor. The telescope was at a tilt of about 45 degrees, its huge setting circles and giant counter weight being some of its most noticeable features. Perhaps one of the most unusual aspects of this room was the fact that the whole floor moved up and down with the constantly changing attitude of the telescope. The observer could always be within reach of the tailpiece. Our guide punch buttons on a console and the floor changed elevation by nearly a foot almost without sound. As an engineer I found this impressive. Several instruments were mounted at the tail piece, the telescope being only rarely used for visual observing. Long past are the days of Bernard staring through the eyepiece of this colossal refractor straining his eyes to see movement in distant star clusters. Now a days this scope is used to test new imaging equipment and to measure the proper motion of stars. Ah, all this sounds good, but for one quick look through the eyepiece a lonely planet, a distant double star or a brilliant cluster! Needless to say we asked, but few are allowed to look through the instrument.
I can still dream, can’t I?