Monday, 28 April 2008

2008 ACC Lacrosse Championship: UVa vs Duke

Filed under: School, Sports — Tags: , , , — George Privon @ 09:19

Yesterday was the Championship Game of the 2008 ACC Lacrosse tournament. It was a pretty good game. Virginia’s defense made some stupid mistakes early on, which lead to easy Duke goals. However, other than these stupid mistakes the two teams were fairly evenly matched, having similar numbers of shots on goal.

Going into the 4th quarter, UVa was down 11-4. However, we scored 5 goals, bringing us close. It was a very exciting 4th quarter with lots of fast-paced action. However, ultimately we were unable to close the gap and the game ended 11-9, Duke.

ACC Lacrosse Championship: UVa vs Duke on Flickr

Sunday, 27 April 2008

Optical/IR Instrumentation: Measuring Focal Lengths

Filed under: School — Tags: , , , — George Privon @ 09:19

The results of our fourth Optical/IR Instrumentation lab have been put online. The main portion of this lab involved measuring the characteristics of everything in a “bag o’ optics”. This collection of slightly defective optics contained a variety of lenses, lens combinations, flat pieces of glass, and diffraction gratings.

Astr512, Spring 2008: Group Beaton/Fields/Privon/Whelan Lab 4

Saturday, 26 April 2008

Fan Mountain Public Night


Sunset at Fan Mountain

Originally uploaded by GeorgePrivon

Last night was the semi-annual Fan Mountain Public Night held by the University of Virgina’s Astronomy Department. As you can see from this picture of sunset (with the RRRT in the foreground), it was rather cloudy. Fortunately it cleared up for a little while, enabling the 40″ and 31″ telescopes to look at Saturn and M3.

I helped guide tours of the 40″, and it was quite nice. Everyone seemed very interested in the telescopes, especially the many kids who were there.

We were planning to observe some galaxies in the near-infrared using UVa’s FanCam NIR Imager after the public night. However, it clouded back over while we were putting the camera back on the telescope and were ultimately unable to make any observations. Oh well, that’s how it goes sometimes! We’ll try again next week…

Friday, 25 April 2008

Building an Atmosphere

Filed under: Astronomy, School — Tags: , , — George Privon @ 10:22

The stellar astrophysics course I am taking has been progressing well.. we’ve been covering lots of material and it’s been quite interesting. The semester culminates in a project to write computer code to model the atmosphere of a star. Late last night I finally finished my code after several days of almost continuous debugging. Now, with a calculated temperature profile of the atmosphere, my program calculates the mean intensity of the radiation at a range of frequencies (covering the the near infrared through part of the UV) at a variety of the depths in the atmosphere.

In order to solve the radiative transfer equations, we used the “Eddington Factor method” in conjunction with the “Feautrier method”. The Eddington Factor method relates the mean intensity of the radiation field to the a value similar to the radiation pressure. The Eddington factor method allows one to calculate the radiation field using knowledge of the temperature distribution and opacity in the atmosphere. Once you have the mean intensity, the Feautrier method allows you to take the mean intensity and turn it into a quantity resembling the intensity along specific angles. This can then in turn be used to refine the values of the Eddington factor, and recompute the radiation field until it converges on a solution which is consistent with the temperature distribution.

A check can be made on the temperature distribution by comparing the actual flux as a function of depth with the expected flux. This allows one to correct the temperature distribution. With the corrected temperature distribution, you can recompute the radiation field as above.

My writeup (including graphs) is available here. If there is interest in seeing my code, post a comment.

Tuesday, 22 April 2008

Online Stellar Astrophysics Book

Filed under: Astronomy, School — Tags: , — George Privon @ 10:25

One of the resources for my course on Stellar Atmospheres is this book by G. W. Collins II which is available online. Formerly a print book, it is now freely available online. It is a grad level textbook, but worth skimming at any rate.

The Fundamentals of Stellar Astrophysics (by G.W. Collins II)

Sunday, 20 April 2008

Watching Parix-Roubaix Carnage

I had a nice relaxing weekend here in Charlottesville. My parents were in town for my Dad’s Darden Class reunion and it was great to spend time with them. We went to the UVa Astronomy Department’s public night at McCormick Observatory on Friday and got to look through the telescopes up there. The Clark 26″ telescope was trained on Saturn. The rings were clearly visible along with 5 moons. It almost looked like a picture!

Yesterday was the Astronomy Department picnic at Fan Mountain. It was nice to relax in the sun and enjoy good food and good company. Sprinkles of rain starting coming towards the end so it was good timing.

My parents headed out this morning, back to Idaho. So now it’s back to work for me. There’s two weeks of classes left, then finals, and then summer! I’m anxious to finish classes so I can get back to doing research. With the workload now, research has all but ceased. I have plenty of research related work, but it’ll have to wait for summer unfortunately.

As far as school goes, I have a few major projects left before the end of the semester, and one more problem set. By this Wednesday my model atmosphere of an 8 solar mass star should be completed. This model includes ionization of hydrogen and helium atoms in the atmosphere of the star, as well as doing simple radiative transfer. The code is quite involved, but very instructive.

The other project (which hasn’t been well defined yet) is for the Optical/IR Instrumentation class. It will likely involve putting together and testing a single-pixel detector. Also quite involved, but should be quite interesting!

Right now, I’m taking my final break before starting to work again… the 2008 Paris-Roubaix bike race is on TV, and I’m watching the carnage. The cobblestones are taking their toll and there’s been lots of crashes so far. Quite an intense race. Unfortunately it’s tape-delayed at least a week, so I already know the results. But, should be exciting to watch the action anyways!

Sunday, 6 April 2008

Lazy Weekend

Filed under: Virginia — Tags: , , — George Privon @ 23:12

Didn’t do much this weekend. Sat inside (and ran some errands) on Saturday because I thought rain was imminent. So, I didn’t ride.. Naturally, it didn’t rain all day. Then, when my ride was planned for Sunday, it poured all day today. Did work on some homework though.. For our instrumentation class we have a “grab bag” of dysfunctional reject optics (lenses, prisms, etc) which we have to characterize. So my group multi-tasked. I focused on re-running our bar cooling experiment while the rest of the group measured focal lengths and physical dimensions on the various optical elements. There was quite a wide variety and it was interesting to see.

Only 3 more weeks left in the semester.. can’t believe it’s almost over already.

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