May 19

Today we took two tours of telescopes. In the morning, we went to the McMath-Pierce Solar Observatory which is a really cool set of three telescopes that I wrote a paper on. These telescopes observe the sun (and other very bright objects at night) and this observatory has lead the solar astronomy community for a long time, considering it has the largest diameter mirror (1.6-meters) of any current solar telescope. There are a ton of different instruments that can be attached to this telescope and the beam is directed down a really super long tunnel before getting reflected by another mirror. This huge focal length was originally developed to get the best resolution for the photographic plates that were used at the time. With modern CCD detectors, such a long focal length is not really necessary, but it is still a cool building.

Afterwards, we went back to the 4-meter telescope again to get a bit more of an up close and personal tour, and we got to go into the instrument cage that sits behind the mirror. The telescope is on an equatorial yolk mount which means it has one axis fixed along the north pole (thats the equatorial part) and the rest of the telescope moves around along this u-shaped steel beam (the yolk part) that allows very smooth movements. The beam is coated in a layer of oil and is essentially suspended on the oil in the supports, so when it moves around, you might not notice unless you were watching because it is so quiet. 

Today’s Lecture: Cosmic Ray Detector Arrays. Cosmic Ray detection is a really cool area of astronomy where we try to gain information about very high energy astrophysical sources by analyzing a cascade of particle interactions and decays in the atmosphere as very high velocity H and He atoms smash into atmospheric particles. These atmospheric particles break apart into muons, some of which decay into gamma rays+other particles. Detectors on the ground detect the gamma rays and high energy charged particles that make it down to the ground. Sometimes we are able to observe something called Cherenkov radiation. This radiation is basically an electromagnetic sonic boom caused by very high energy charged particles that emit radiation. The particles are so  high energy that they are traveling faster than the local speed of light (speed of light can be violated in a medium, only absolute speed of light is sacred), and then when these super-luminal particles emit radiation, the radiation is basically doppler-shifted to the blue.