Not Your Dad's Telescope
On Wednesday night/ Thursday morning, I was invited by Dr. Ertel to attend one of his observations. Dr. Ertel and the other astronomers had been doing observations for the past week, so their sleep schedule was prepared; however, mine was not. I awoke at 1 that night after a short nap, and I went on my way down to the Steward Observatory, hitting no traffic at all, quite an enjoyable commute. Upon arriving, I was guided to the fifth floor of the Observatory, which is on campus. What I saw surprised me. I expected to see dozens of people dressed very nicely, using hundreds of instruments. Instead what I found was five people in a conference room, dressed comfortably with snacks, laughing and having a good time, albeit with a pretty elaborate computer setup. I realized at that moment that astronomy isn't as rigid of a field as I had originally thought. The work that Dr. Ertel was doing became more accessible and less frightening because I saw how relaxed the atmosphere really was.
Don't let this deceive you! the equipment that this group was using was astounding, groundbreaking technology. The telescope that they used was the LBT in southeastern Arizona. Of course, this massive telescope was not mounted at the Steward Observatory, the astronomers were remote accessing the telescope from a conference room at the University.
Now, the LBT or Large Binocular Telescope is an interesting piece of equipment, so called as it is constructed of two congruent mirrors of 8.4 meters across and 14.4 meters between the centers of each mirror.
The two mirror design allows the LBT to achieve the detail of a 22 m telescope. The theory behind this telescope is something known as adaptive optics. When the light from bodies in outer space passes through the earth's atmosphere, this light becomes distorted and does not allow for a clear picture. To draw a more well known example, imagine a hot day, not too hard for us in Tucson, and think about what you see when you look at a road in the hot sun.
You can see the "heat" because the pockets of hot air near the road change the path of the light and make the object you are seeing look blurry. This is the same principle as with the telescope. The light from those bodies is distorted by pockets of heat in the atmosphere. Astronomers describe how "bad" this distortion is by the term "seeing". The LBT was designed to combat this. While many other telescopes will compensate for this distortion later on in the observation, the LBT corrects this issue before the measurement is taken. This is done using a deformable mirror. The University of Arizona is home to a world-renowned mirror lab. I was blown away when one of the astronomers described the mirror to me.
The deformable mirror at the LBT is only about the width of a contact lens, incredibly thin, and is made of hundreds of small pieces of contact lens thin glass. Behind each piece is an actuator which can manipulate a small piece of the massive 27 foot mirror. A wave sensor senses the waves of light coming from space and compares them to those of a point source.
Through many advanced calculations and lines of code that I won't pretend to understand, the deformable mirror is shaped such that the light rays that bounce off of this mirror produce a clear, less distorted image. Watching the graphic showing the mirror deform in real time was a amazing. Unfortunately, I cannot find an image or graphic that really does it justice, but imagine waves slowly rolling across a surface in a beautiful pattern, then imagine that to be glass and it becomes even more impressive. Through this type of correction, the LBT is able to achieve clarity better than the Hubble Telescope.
With that introduction to the LBT, let me now get to what we were observing, a comet. However, early in the night, the observation became difficult. Dr. Ertel told me that, due to a recent storm at the observatory, the "seeing" (the one I mentioned earlier) was not adequate to be able to observe. He told me that the seeing should be around 1.5 for the astronomers to be able to using the adaptive optics of the LBT to correct for the distortion. At around 3 a.m. however, the seeing was around 2.5, much higher than the astronomers could correct for. Therefore, a good portion of the night was spent trying to figure out how to lower this number. This included opening the vents to allow the wind to pass through the telescope as well as just waiting for the seeing to get better. Eventually it did, and the astronomers were able to begin collecting data on this comet. Even when I left at around 6:30 in the morning, Dr. Ertel was still working hard gathering data on this comet. The astronomers were quite excited because this would be the first time that a comet had been observed with a telescope of this caliber.
In the end, the experience was much more enjoyable than I had originally anticipated, and I was glad that the night yielded some results. The next observation will be in April, so there will not be much more news about them until then. The observation constituted the majority of my work on the project this week. I look forward to doing more work on this project and maybe doing another observation sometime.