Last Thursday (24th of October 2013) I gave a talk to Swansea Astronomical Society. This is the third year in a row that I have spoken in the autumn to this wonderfully active society on a historical theme. Two years ago I spoke about the early history of Yerkes Observatory (I blogged about that talk here), and last year I spoke about George Ellery Hale (my blog on that talk is here).
This year I continued the Hale theme, speaking about the history of Mount Wilson Observatory, which Hale established in 1904 after resigning as Director of Yerkes Observatory. Mount Wilson Observatory is most famous of course for its 100-inch telescope, the telescope used by Hubble (and Humason) to discover that the Universe is expanding. The Observatory is located just outside Los Angeles, and despite the light pollution of LA, it is still a very active observatory. This is mainly due its exceptionally stable air, giving it image quality better than pretty much any other observatory in the continental USA.
My connection with Mount Wilson Observatory is not as strong as my connection with Yerkes, but I was lucky enough to be awarded a Mount Wilson Fellowship in late 1999 and so went to use the famous 100-inch on four separate observing runs in 1999/2000. I was using an adaptive optics system, the plan was to study in unprecedented detail the structure of the scattering of visible light from dust grains in reflection nebulae. Unfortunately we were not able to use the AO system to do this work, as the central stars illuminating the reflection nebulae were too far from the dust regions we wanted to study for the AO system to work. In addition, our primary target, NGC 7023, is located at too high a declination for the 100-inch with its yolk mount to be able to reach. I thus undertook an alternative observing programme of observing close binary star systems to determine their orbital properties, systems which were too close to be resolved with conventional telescopes not using an AO system.
During all of these four observing runs I do not remember seeing the stars twinkle when it was clear (which it was most nights), which is testimony to the incredible seeing the Observatory enjoys. Even way down towards the horizon, the stars remained rock steady to the naked eye. It is because of this exceptional seeing that Mount Wilson was the testing ground for Adaptive Optics systems, and is now the testing ground for optical interferometry, with projects like the CHARA project run by Georgia State University (see this link for more information).
Here are the slides from my talk. I hope you enjoy them, and of course if you have any questions please feel free to ask in the comments section.
Here is a video of my talk. Apologies for the quality.