University of Arizona Adult Astronomy Camp
by Fred Quarnstrom
Don McCarthy with the model of the thin meniscus mirror.

A short taxi ride from the airport placed me at the Alumni Association building of the University of Arizona.  I had left Seattle at 6 AM and arrived in Tucson via Denver 20 minutes earlier.  Our adventure at adult astronomy camp was to start promptly at 1 PM.  Dr. Don McCarthy came through the door a few minutes later with abright red Edmond's Astroscan  telescope under his arm.  Don is an  Astronomer at The Steward Observatory, a professor in astronomy and one of the team that designed and uses one of the latest additions to the Hubble telescope, the Near Infrared Camera and Multi-object Spectrometer (NICMOS).

He introduced his camp staff, all graduate students, on their ways to PhDs.  The 6 looked like they belonged as a YMCA summer camp staff, ponytail jeans, shorts etc.  The campers were a cross section housewives, a dentist, a couple of medical doctors, a few wives who came with there husbands, several retired folk and a school teacher.  The common thread was an interest in astronomy, however, several were just starting and had little experience.

We were driven a short distance to the planetariumat the Flandrau Science Center where we  reviewed directions, meridian, zenith, altitude measurements and were introduced to the stars we would see in the sky later that night.  Larry Dunlap did a particularly good job of centering our attention to the square of Pegasus describing it as a baseball diamond and guiding us to areas of interest in Left field right field first base if the runner turned right after crossing first base etc.

We next visited the Steward Observatory Mirror Laboratory mirror lab under the football stadium.  I expected we would be able to see the mirrors through a window and was not disappointed.  They were in the process of polishing a 6.4 meter mirror and the area was only accessible via a window.  It was a little shocking to see one of the technicians walking on the mirror with padded shoes with a push broom cleaning the mirror.  Note the person cleaning the mirror with a bush broom.

Within a few minutes however we were taken to where another 6.4 meter mirror and a 8.4 meter mirror blanks were sitting waiting for grinding.  It is hard to relate to a mirror that is over 27 feet in diameter.  Both mirrors had focial lengths of slightly more than their diameter f= 1.25 and 1.14 This lab has pioneered in the use of silicon forms that leave the back of the mirror looking like a bee hive.  The open cells are about 6 inches across with walls that are 1/2 an inch thick.  the top of the mirror has a glass slab that is about 2 inches thick, the same as my 10" mirror.
Over a 1000 alumina-silica fiber forms create the honycomb form of the mirror.

  Metal mount plates are attached to the back of the mirror withsilicone much like the mirror in my 10 inch scope.

It is hard to relate to a mirror that is over 27 feet in diameter.

The form is placed in an oven after being loaded by a borosilicate pyrex type glass once the glass is melted about the consistency of honey the oven starts to rotate at 7 rpm.  This cause the molten glass to climb up the walls of the mold giving it the shape of a parabola.  The front surface of the mirror will be within millimeters of the final shape when it comes out of the oven.  The oven is slowly cooled until the glass has set.  The oven stops rotating at this point and the temperature is slowly brought to room temperature over the next 3 months.  Once the mirror is cool, high pressure water jets are used to remove the forms from the individual cells.  The resulting mirror weighs about 1/6 of what a solid mirror would weigh.  There I was standing with in touching distance of the largest mirror ever cast.  If the look closely they probably  will find more than one of us was drooling.

These mirrors may be a thing of the past if future research shows it is possible to form a thin mirror, 2 to 3 mm thick that is  suspended on posts that deform it into parabolic shape.  These meniscus mirrors will be very light weight.  After all it less than a ounce of aluminum that does the reflecting,  It just takes tons of glass to get an ounce or so of aluminum film in the correct shape to reflect and focus our light beams.

For the next hour and a half we would our way up into the mountains north of Tucson to Mt Lemmon.  The summate is relatively flat and 9200 feet in elevation.  Most of us found we moved a bit slower if we did not want to be out of breath.  The summit is occupied by and old Air Force facility, several building for sleeping, a kitchen and a half court basketball court, as if any of us flatlanders could have played.  There are 6 telescopes at the summit. We enjoyed a dinner of lasagna, pasta, ravioli , salad and cheese cake.


At sunset, we first watched the space shuttle and Miur pass overhead and then headed to Mt. Biglow  for an evening of observing with the 61"  telescope.  There were a number of pairs of binoculars and two 10" Meade LX200 also set up for us to use.
The arrow marks the site of the telescope on Mt. Bigalow.
The 61" is an amature's dream.

The floor adusts so everyone's eye is at the proper level to get a good look through the scope. That is me at the eyepiece.

The campers were all encouraged to use the controls, with help from the staff.

The 61" was built to get good films of the moon prior to the moon lander missions.  It is computer controlled housed in a dome that must have been close to 40 feet in diameter.  It has an hydraulic floor lifts or lowers the observer to the proper height to reach the eye piece. To say we were spoiled is an understatement.  We viewed Jupiter- spectacular, Saturn a jewel, Neptune, Uranus, many planetary nebula and at 4 in the morning the Orion Nebula.  I actually felt I could see some of the red color you see in photos.  Part of the group left for the barracks at about 1 AM the rest of us spent the night until the sky was starting to glow toward the East.

Don is shown holding jupiter about the size of a pea with its 4 moons attached to a wire.

Don sets the location of the sun for our model universe.  The sun was a 3" yellow ball.

Breakfast was at Noon followed by a discussion of the emptiness of space and an exercise of laying out a miniature solar system.  Neptune was half a mile a way well on the way to a forest lookout so we went on to enjoy the view before huffing and puffing our way back up the mountain.  The air is noticeable thinner at 9,000 feet.  That afternoon we viewed  the sun and solar prominenances with a H alpha filter on a LX200 and a projection image from the Astroscan.  Back for another discussion of the evidence being used to show there are planets around other stars.

Don and his staff were truly amazing with there descriptions.  All 6 were very bright folks who understand astronomical concepts and are able describe them in ways we were able to understand without resulting the math and physics calculations that I have forgotten from my college years 38 years ago.  They made very complex topics understandable and seemed to genuinely enjoy answering our questions.

Our second night of observing was again started by watching Muir.  However, this night there was a satellite moving North to South that intersected Muir's path.  We knew as we watched the two converge on a collision course that one was probably many miles higher than the other but it was some relief to see them pass without a collision.  That night was again an all nighter for some.  This evening there was also a SBIG ST7, ccd camera  set up to demonstrate ccd astronomy.  At 1 AM I left for the barracks two all nighters is more than I can handle.

Sunday it was pack up your stuff and ride back to Tucson.  From there it was an hour to the Southwest and Kitt Peak.  We visited the gift shop to see the fixed displays.  The glass core that  was cut from the 4 meter mirror was on display.     It is almost 2.5 feet thick. The National Solar Observatory was next.  we entered the tunnel that goes many hundred feet into the rock to a mirror that reflects and focuses the sun back up the tube to another mirror which directs the image down into an observing room where the image of the sun is about a yard across.

The white box behnid the blue yolk holds the mirror and what a mirror.
Our next stop was the 4 meter scope.  We crawled over under the scope  and into the ccd cage.  We were shown images of M 33 that were taken the previous night.  We saw the aluminizing (I think that is a word) vacuum chamber, machine shop, control rooms.  If it was there we saw it.

We ended our day watching a sunset and for the first time in my life I saw the "green flash." 

The flash was confirmed by several others in our group.  Once the sun was down we had our farewell dinner at the University of Arizona dormitory on the summit of Kit Peak and started back to Tuscon and the real world.  What a weekend.