Pluto Occultation Coolidge , AZ 16-18 March 2007

A lot can be learned about an object when it passes in front of a star. By observing how the star dims, it is possible to determine if the object has an atmosphere (if it doesn't, the star will suddenly just disappear; if there is an atmosphere, it will fade before disappearing), and potentially something about the structure of the atmosphere. You would think that with all the stars in the night sky that Pluto would pass in front of a lot of stars. Turns out that Pluto in fact is small enough that this doesn't happen very frequently. And when it does, usually the shadow it casts can only be observed from an inconvenient location. That was not true of the occultation on March 17-18. The path was initially predicted to go through the central part of Arizona. So when a friend invited me to observe at Central Arizona College, I immediately made reservations to fly out, and packed my CCD camera for a vacation consisting of several sleepless nights of observing.

Unfortunately, we had high clouds most of the night, so the quality of the pictures we took were terrible. Even more unfortunate, the predicted path was wrong - the center line ended up WAY north of us. But when I processed the data, I was still able to see the dip in the light from the combined star/Pluto. If you are interested, I have on the order of 800 shots taken with the CCD camera spanning the occultation, plus some data taken the night before, and other accompanying information such as exposure times, timing notes, exact location, and sort forth.

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