One City, Two Worlds: Countdown

Whenever I walk alone along the streets of Santiago, I suffer from periodic episodes of disorientation. Is it the noise? The pollution? The fact that I hardly speak the language of this country? All plausible reasons, of course. Then again, living in a foreign country, I would fully expect to encounter the unfamiliar on a daily basis. No, the reason for my disorientation is the fact that Santiago already feels intimately familiar to me. The urban sprawl; the view of snowcapped mountains on the horizon; the crowded city center and well-to-do suburbs; the one-way streets lined with merchandise stands and street peddlers; even the ethnic enclaves scattered throughout downtown--every part of Santiago feels like home all over again. If I had the time and the means, I would even attempt to drive from the powdery snow of the Andes to the white beaches of Viña del Mar just to pretend that I was back in Southern California. It's possible that I'm only taking to Chile now that I have less than a week left before I head back to the hot and humid Northeast. But assuming that my sentiments are not misguided, I'm pretty sure that given the chance, I would enjoy staying here longer, living by myself and doing the things I love.

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Speaking of the things I love, I just realized that I haven't really written anything about the astronomy that I do here--despite the name, title, and subtitle of this blog, and the fact that I never would have had the opportunity to come here in the first place if not for astronomy. Oops.

I guess most significantly, I've come to appreciate how different classroom knowledge is from the analysis of real data using professional reduction and photometric software. It's one thing to know that variable stars exist, and another thing entirely to take hundreds of images, each containing hundreds of stars, and determine which (if any) stars vary intrinsically rather than due to atmospheric disturbances. It can be a tedious process, but producing a smooth and beautifully periodic light curve at the end makes everything worth it.

It's also not a coincidence that I chose variable stars to illustrate my newfound appreciation for real-world astronomy. The two labs we've completed so far have both involved finding variable stars in a sky field taken across different epochs. The process is conceptually pretty basic. First, I debias and flatten the images (i.e. correct for random background noise and differential pixel responsiveness in the detector's CCD). Then, I align the images either relatively, using the first image, or absolutely, using a catalogue of stellar coordinates. Then, using photometric software, I obtain flux or magnitude values (measures of luminosity) for the stars that exist in every frame, and import the data into Excel. Finally, I plot these magnitude values against time to determine which stars are variable (or at least seem to be).

What makes the process more difficult than it sounds is the fact that every step in the sequence, from connecting to the data server to writing scripts that analyze hundreds of images at a time, is completely new to me. More frustratingly, every lab uses its own program language and proprietary software, which means that I probably won't be able to use the skills I learn here for my thesis project, much less my eventual career. On the other hand, I'm having fun learning how to use Linux, Perl, a ridiculous program called SEXTRACTOR (Source Extractor), and all sorts of other useful tools, so I shouldn't be complaining.

The types of images I work with. Ignore the labels; they're meaningless without the accompanying lab report.

Light curve of EH Librae. The black lines are observational error bars. (Let it be known that I hate observational error. It makes life so much harder.)

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And finally, it's about time for another photo upload. Some of these are Joey's, but I don't remember which (except the ones of me, of course), so I'm crediting him here. Yeah artistic honesty.