Multiwavelength Astronomy

Photo of Nick Woolf

Optical Tools, Nick Woolf

Multiple Mirror Telescope

I moved to the University of Arizona in Tucson from the University of Minnesota because I thought there would be more opportunities for research here. That’s where I started to work with Roger Angel, and shortly after I arrived we started looking at spectral variation of polarization of radiation from a Seyfert galaxy, which is a sort of mini quasar. We discovered that there was a lot of dust created around the core of this quasar, and it’s a fairly common process that happens. As part of the disturbance, it seems there are bursts of star formation. We were able to do this because Roger wasn’t afraid of making novel optical instrumentation and neither was I.

We collaborated on work like this and then suddenly in 1978 the Multiple Mirror Telescope (MMT), which was being developed in Arizona, came to a crucial stage in its development. It was nearly ready, but there was not yet a director, and there were decisions that had to be made and very little money! Did one put the available money into a cooling system for the concrete slab floor below the telescope, which it was assumed would result in sharper images, or should we use these limited funds get the telescope ready for observing? I was given the job of acting director to sort out which should be done. I looked into it, analyzed the problem, and decided that the appropriate thing to do was not to cool the concrete, but to insulate the floor with wood and carpeting. We went ahead with this and managed to get the telescope into operation. We got it into operation so fast that we had to do some patching with black plastic sheets to try to shut out light leaks!

Multiple Mirror Telescope: In this image you can see the six segments of the telescope mirror.

Multiple Mirror Telescope: In this image you can see the six segments of the telescope mirror.
Credit: Steward Observatory Mirror Lab

There were six mirrors in the MMT at that time; it’s been changed since then, but you could see the images formed separately by the six mirrors, and it was noticed--it was very strange--there were a couple of mirrors for which the images were much fuzzier than for others. And it was then found that there were places where warm air was coming up between the black plastic sheets, and that air was impinging on these mirrors. We realized then that it was not just a matter of keeping out the heat from the floor, but that heat played a huge role in whether you had good or bad images. We started to focus on this for the MMT, and that became my next optics project: understanding what was going on and working with this.

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This material is based upon work supported by NASA under Grant Nos. NNX09AD33G and NNX10AE80G issued through the SMD ROSES 2009 Program.

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