Astronomy Day 1999 at The Tech Museum of Innovation



Before the event, I collected all the stuff together (thanks to Crazy Ed, Jane and Akkana for their donations) and pre-built some of the parts. (Here are some pictures of the parts taken before the event.) Then on Saturday morning, May 22, we all descended on The Tech to grind the mirror and construct the scope. (We also had a few complete scopes set up for display and some solar scopes doing their thing outside.) Our goal was to show the ATM process to the museum visitors and see the Moon with our new scope before closing time on Sunday. We let everyone who wanted to help grind and polish. Those who did got to sign their names on the tube. By the end of the day Sunday, the tube was covered with signatures. It will officially be loaner scope #32 but we'll always know it as the Signature Scope. And we saw the Moon, too! .....

Here are some pictures from the event.

Bill's funny ideas about carpentry caused a few other snags, but nothing that can't be fixed. I had carefully measured and balanced the tube and drilled holes for the side bearings. But when I put down the tube for people to sign, I put it upside down. So it was either upside down signatures or drill new holes for the bearings. The signatures won. Then someone convinced me to drill the holes a little higher up from the mirror end (to allow for a future finder scope) but that meant (and we didn't think of this at the time) that the side boards weren't tall enough and the scope wouldn't point to the zenith without hitting. It was a good thing that the Moon wasn't too high!

I had a brief panic when we couldn't find enough screws to attach the side teflon bearings. I ran half way around the museum looking for two silly wood screws with no luck. But it turned out that Dave had used them elsewhere and all we had to do was swap them around.

But the dumbest thing was that we used an eraseable pen for the signatures. A lot of them got kind of smudged. But it should be OK after a little clearcoat.

Here are some pictures of the mirror. It appears that we succeeded in making a paraboliod, though it is not yet clear how good the figure is. We'll probably want to mask the outer 1/8" or so. But I'm guessing that it will be serviceable. We had originally planned to do some more polishing and figuring but if it tests out OK we'll leave it alone. That way it will remain mostly the work of the Tech's visitors.

But by golly, you really can make a working telescope in 14 hours! John Dobson ought to be proud.



Jane Houston wrote a much nicer article about this for the Ephemeris.

Many months later.....we finally got around to finishing the last few details. Dave masked the outer edge of the mirror (making it really a 5 1/2 inch f/7.6) and we added a little weight to the tail end to balance it up better. We added a unit power finder and Jim Bartolini did some finishing.
SJAA home Bill Arnett; last updated: 1999 Dec 28