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Showing posts from July, 2013

Project Minerva: The hits keep on coming!

Project Minerva co-investigator and former student-mentor of mine, Prof. Nate McCrady, recently won a large grant from NASA's Experimental Program to Stimulate Competitive Research (EPSCoR). w00t!! The funds will be used to pay for student and staff salaries at U. Montana to work on the project, and to purchase one of the four Minerva telescopes.  From NPR: NASA recently awarded a 1.125 million dollar grant to researchers at the University of Montana to explore, among other things, whether there is life on other planets.  UM will join with three other universities around the country to take part in "Project Minerva", which will use an array of four telescopes to research so-called "exoplanets". UM Associate Professor of Astrophysics, Nate McCrady, will lead the effort in Missoula. In this feature interview, McCrady talks with News Director Sally Mauk about the study of exoplanets - planets that orbit stars other than the sun. Listen to the interview on the Mont…

Whoa! Factor 9: A view of home from space

The NASA Cassini-Huygens mission is a space craft sent to orbit and study Saturn and its moons. It was launched in 1997 and finally arrived at Saturn in 2004. It's first task was to launch the Huygens probe, which landed on Saturn's largest moon, Titan. The Cassini orbiter is now studying the structure of Saturn's rings, among other tasks.

About a few days ago I received this email from Geoff Marcy:
Dear All,Today, on July 19, the NASA "Cassini" spacecraft at Saturn will point at Earth and take a picture.   The idea of the image is to highlight how fragile and beautiful the Earth is within the vast, cold, darkness of the universe. Our colleague Dr. Carolyn Porco is the head of the NASA Cassini imaging team.
NASA and Porco will be pointing the Cassini spacecraft camera at Earth on July 19 at 2:30 (pacific). They will take an unprecedented planned and publicized image of the Earth and our Moon next to Saturn and its ring system: http://diamondskyproductions.com/rece…

How to read a scientific paper

Here are some very handy instructions on how to read a scientific paper, which I give to all of my undergrads and first-year students:

http://www.biochem.arizona.edu/classes/bioc568/papers.htm

Technically, it's written for biology students, but it works equally well for astronomy/physics students. The topics covered include:
1. How are papers organized?2. How do I prepare to read a paper, particularly in an area not so familiar to me?3. What difficulties can I expect?4. How do I understand and evaluate the contents of the paper?

I learned Python!

From xkcd, via Tim:


Moving. Again.

I started this blog back in 2007 sitting on an empty floor, in an empty living room in Albany, CA, my laptop perched on a cardboard box filled with our stuff. I started writing this blog to distract me from the sadness of leaving. I was mourning because of what I was leaving behind. I even knew that the things I was leaving---classmates, student housing, my Campbell Hall office---weren't permanent. My friends were moving on, too. Heck, my office was about to be torn down. Berkeley, CA was going to move on even if I didn't. I knew this. But it didn't make it less sad. So I started writing, and I haven't stopped.

And here we are again. Another house full of moving boxes. But this time I'm not mourning alone. It hit Owen, too. Owen found an artifact of our old familiar life, one of the old blankets that used to be a permanent fixture of our couch, lying on the floor of the closet. We sat together in the darkness on the blanket, and we cried, together. We cried for the…

Chemical Calisthenics

I was this Wired article about using hip hop to teach physics and math. Definitely a good read. In the article there was a link to the Blackalicious video shown below. My good friend Pat gave me the heads-up about the group back in the early oughts, but I mostly forgot about them because Blazing Arrow and Nia somehow failed to make it onto my iPod (I need to figure out what went wrong!).

So many excellent tracks. A-to-Z. Tomorrow. The Sky is Falling. The brilliant story-telling of Cliff Hanger. But I never got to see a video until tonight because I came across the music in the pre-Youtube era.

Anyway, I present to you Chemical Calisthenics. Bombalicious:

Fun with sub-Nyquist sampling (or Aliasing as Art)

A subwoofer agitates a stream of water at 24 +/- $\epsilon$ Hz, where $\epsilon \sim 1$, while video is recorded at a frame rate of 24  Hz (i.e. sub-Nyquist). Fun ensues!



This effect is known as aliasing, which is also responsible for helicopter blades and car wheels appearing to spin backwards in films. Aliasing is also important in finding planets. We sample the radial velocity variations of stars caused by their planets using instruments such as HIRES at the Keck observatory. If we don't sample with dense enough time coverage (high enough frequency), a sub-sampled radial velocity signal can appear at a shorter or longer period. Here's an example from Wikipedia:


Imagine that the red curve is the true signal and the apparent (measured) signal is blue. You gotta mind your time-sampling! The optimal sampling is less than half the period (twice the frequency), which is known Nyquist samling.

This is what caused planet hunters (including me) to get the orbital period of 55 Cancri…