Observatory 7 – Kitt Peak, Part 1

Okay, right off the bat, you can see my annotated pictures of Kitt Peak >here.<

I am now writing this in March, so –– Good Lord, it’s more than six months since I was there??!!! I didn’t write much in my journal at the time, or here. Fortunately, I did add some commentary to the pictures linked above. Well, let’s see how much I remember.

The National Optical Astronomy Observatory at Kitt Peak is about an hour’s drive and change west of Tucson. They run three tours through the day most days: the solar observatory, the 2.1 meter, and the 4 meter. They open at 9:00 a.m. and tours start at 10:00. It was my intention to get there for the tours, because that was sort of the point of being in Arizona, so I was up and out by about 8, which is pretty good for me. Had breakfast from McD’s in the car, which was about the worst food I had on the whole trip — except for breakfast on the Capital Limited. After driving about an hour on that beautiful morning, I was starting to see some mountainous terrain pop up, and not much later started thinking I was seeing a shiny white or silver dot on top of one of the mountains. As I got closer I became convinced it was a dome. Sure enough, I soon came upon the turn off to Kitt Peak! I was very excited. The road up the mountain was quite a drive, a bit of a white-knuckler in places with some pretty serious switchbacks and sheer drop offs. Nevertheless, I made it safely to the top.

One of the first things I noticed when I got out of the car in the parking lot was that it was very, very quiet, except for some wind in the trees. I liked that. Which is good, because I spent all day and a good bit of the night there. Well, about twelve hours or so. I made my way to the visitors center, which is a small brick building with a beautiful mural, a fair sized patio with some tables and benches and sciency things, and an observatory dome on the roof of the building. Inside, it is filled with sciency displays in about 2/3 of the space and a gift shop in the remaining 1/3. Went to the counter and paid for the three tours ($15 for the lot) and for the evening observing program ($75). There were two choices for observing, a general objects and deep sky program and “Our Marvelous Moon.” It still being the monsoon season, I had reserved a spot for the moon program as I figured you can see the moon pretty well even in pretty bad conditions, but you can’t see all the faint fuzzies unless it’s pretty good.

Tour #1

The first tour was led by docent Katy, who is a professional astronomer, retired with 50 years experience. She was very knowledgeable as you might expect, and very engaging, as you might not expect. About 15 people had appeared for the tour, which began in the center with a little history about how the site was chosen, negotiated with the Tohono O’odham Nation, and developed as the National Observatory. The object of the tour was the McMath-Pierce Solar Telescope, which had been retired earlier in the year. It is fascinating design and an exceedingly large instrument. As you can see in the pictures, there is a large vertical column connecting with a diagonal structure that extends underground. This diagonal column is north >polar aligned<, that is, it is aimed at the north celestial pole, the point to which the earth’s rotational axis points in the northern sky, like an equatorial telescope mount. Because it is, sort of. Turns out there is a rotating flat mirror at the top of the structure on the diagonal axis, and it tracks the sun. The sunlight reflects off the mirror and down the axis through a 500 foot optical tunnel to a concave secondary mirror, then back half way up the tunnel to any or all of three more mirrors. These mirrors reflect the light down into a variety of spectrograph instruments in a subterranean laboratory (which sounds more evil than it is). We got to look in from an observation room about half way down the optical tube, which looks kind of like a subway station. We also got to go down to the lab, although since it is closed now we could only look in. They did 5 or 6 decades of groundbreaking solar science there, but now it is considered obsolete. So we’re back to the question of what do you do with giant, historic, obsolete astronomy equipment? Oh, fun fact. While we were walking around the solar observatory, half the sky was clear blue and the other half was entirely socked in and producing lightning and thunder, so that was kind of exciting. What happened to that beautiful morning I drove in on?

Tour #2

We made our way back to the visitor center to see if there was anyone new going on the next tour. I don’t remember now if there was or not, actually. Katy led the second tour, too, which was to the creatively named >2.1 Meter Telescope< (that’s about 84″ or 7 feet). It is a large Cassegrain-style reflector on a large, equatorial fork mount. That it is equatorially mounted means the base is at a 32º angle from vertical. As the mirror alone weighs a ton and a half, having this enormously heavy yet super-sensitive piece of equipment standing at NOT perpendicular to its base felt a bit unsettling, like something was not right. Like the angles! (See what I did there?) Any way, this telescope has done lots of groundbreaking science and is particularly notable for being the first scope to use >adaptive optics<. At this point, several months after the fact, I don’t remember why, but I felt oddly bored with this telescope. Maybe it was that Katy spent a good bit of time explaining adaptive optics, with which I was already familiar. I remember being grumpy about that guy in the group who thought he knew more than the PhD astronomer, so maybe I converted my anger to boredom. Maybe I was hungry. I don’t know. Looking back, it’s an impressive instrument that I’d love to have in my back yard.

Break

We returned to the visitor center, and those of us who were staying on (pretty much everyone) could have lunch if we’d brought it, which it says to do in the literature for the tours. There is no food service for visitors. So I had brought some leftovers from dinner the night before at Za’atar, a mediterranean restaurant in Tucson. The weather was stable and pleasant at that point, so we ate out on the plaza. There are a couple of tables and benches, along with a couple cool sundials that have no practical application to lunch. I sat with the woman who manages the gift shop and schedules people for tours and night programs. She was very interesting to talk with. She is a member of the Tohono Nation and active in her church. She told me that she loves the quiet and the peacefulness at the top of the mountain (me, too!), and that people in her church ask her to pray for them while she is at work because she will be closer to God. We were both a little disappointed in their theology, but she prays for them nevertheless. She told me about her family and some of their struggles, so through the rest of my travels I prayed for her. 

Meanwhile the weather began to deteriorate, with clouds and fog moving in across the valley and across the mountain, too. Great. Made for some interesting photos, any way.

Tour #3a

The third tour was to the Mayall 4.1 meter telescope, the largest on the mountain. This part was led by a different docent, named Dave if I remember correctly. We began with some background and history at the visitor center, then moved to the parking lot. Two reasons for that: first, we were driving to the Mayall dome, and second, in the parking lot is a large cement donut with a mural painted on it. I had noticed it on my way in but not really looked at it. It turns out that the donut is a slug the same size and weight as the mirror for the 4.1 meter telescope that was used to balance the scope during construction. Once everything was finished and nothing was likely to fall, then they put in the actual mirror. Once that was done, they had to figure out what to do with a giant cement donut. Rather than roll it down the mountain, they invited a Tohono O’odham artist to do a mural on it, and it was put on display in the parking lot as you walk toward the visitor center. It’s pretty cool on all counts. Dave pointed out that a 160″ disk of glass weighs a couple tons, or at least this one does. What is remarkable is that the aluminum coating on the glass disk that makes astronomy possible is equivalent to about two paper clips, just a few molecules thick. Amazing!

We all loaded in a big white van to head up to the Mayall dome. We hadn’t gotten a quarter mile down the road when someone raced up, flagged us down, and told us we couldn’t go, because it was a hardhat day. They were renovating the dome and moving stuff with cranes, so it was declared unsafe for visitors. Well, that made for a short tour. We ended up back on the patio, and Dave continued his lecture valiantly. Shortly, though, Katy showed up, talked with Dave for a minute, and then excitedly told us they had arranged to let us see one of the other telescopes, the WIYN 3.5 meter.

Tour #3b

WIYN stands for Wisconsin, Indiana, and Yale Universities, and the National Optical Astronomy Observatory (NOAO, i.e. Kitt Peak). The WIYN scope, a large (obviously) alt-az-mounted Cassegrain reflector, is generally not open for public tours, but it was also down for maintenance, so we got lucky. It is about 20 years newer than the 4.1, and consequently it is vastly lighter and more compact and housed in a much more efficient box with shutters instead of a classic dome. Because the mirror was spin cast and honeycombed, it weighs about 1/8 of what the 4.1 meter mirror does. This means the mount can be correspondingly smaller and lighter, and the whole thing is just a lot easier to deal with. It has capacity for detector instruments in three different places at once that can be switched between easily by, well, I guess throwing a switch to move the tertiary mirror. There are dozens and dozens of actuators on the back of the primary mirror, which are not so much for adaptive optics as to correct for stresses when the mirror is tipped at different angles. Engineer Emily gave us the tour. She has been working on this scope since she was an undergrad, and now she’s the managing engineer for it and probably not yet 30 years old.

That concluded the daytime program, three and a half telescope tours for $15. Not a bad deal. I spent quite a while browsing the swag in the gift shop and exploring the displays in the visitor center before the next part of the adventure began.