Sunday, November 27, 2005

Working Hard

Finally, I am working again. By that I mean I really haven’t been for the last year or so. Not to say that I didn’t accomplish anything, I certainly I did some things that I am very proud of. Still, I guess the last year hasn’t brought me any closer to my goal of graduating with a Ph.D. in astrophysics.

Since Clem arrived, I’ve been busy. In the week that I was here alone, I messed around here and there with a few things, but I guess I didn’t really make any big steps, more prep for when he got here than anything else. Well, the last four days or so were long and productive. Our main goal right now is to replace the secondary mirror of the telescope with a new one. I explain (or will explain) this in some more detail in the other blog (A South Pole Adventure). Well, in order to properly install the new mirror, we have to make sure that we place it in the same location as the current one. This is not a simple task given the versatility, or lack thereof, of the foam cone mount. To further complicate things, the new secondary mirror has been fashioned in such a way as to counter an unexpected and unwanted warp in our primary.

In order to make these measurements, we are using a contact coordinate measuring machine, CMM for short and more aptly referred to as the “romer arm”. The romer arm looks much like an arm and has about the reach of a long human arm. At the end of the romer arm is a probe, in our case a ruby ball (made of real ruby for durability). The romer arm works by touching points on a surface with the tip of the probe. The (x,y,z) coordinates of the point probed are then recorded by the machine. Actually, the machine is a little more complicated than that; it really records the angles of the all the joints in the arm. Its kina like how in order to pick up a pencil, your brain tells your shoulder joint to rotate some amount, then your elbow, your wrist and finally your knuckles.

Here is a picture of the romer. It’s mounted upside down here in order to measure the bottom of a part of the telescope. We flip it around to get up into the mirror.

So, I had to climb up into the telescope with this machine, mounted on a special adaptor, and probe out a bunch of points on the primary and existing secondary to properly determine their separation and orientation. The opening in the primary mirror that I had to squeeze through was just a tad bit narrower than my shoulder width and I was standing at first on a 4x4 later on a plywood plank, 4 feet or so above the bottom of the telescope, more than 10 feet above the platform below the telescope. I’m afraid of heights, its true.

Clem went up first to give it a try.

The plank modification…

Measuring the secondary mirror…

Measuring the primary mirror…

Gratuitous photo of my handsome self…

My attempt to take a “scary” picture of myself. Later I realized that these days, I look pretty scary in bright light too.

Nobody else could possibly fit up there; most of those pictures were taken with a timer.

I have some data on the existing setup and probably will have to get a little more. Then the next task is to install the secondary mirror.


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