Post 9lsRS6MLEWhSCL2SHo by anne@beach.city
(DIR) More posts by anne@beach.city
(DIR) Post #9lsNupibmbbHAVtm2C by starkatt@vulpine.club
2019-08-14T05:56:05Z
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So.The sky is really, really big. How do astronomers go from giant sky surveys to knowing what specific objects warrant further study? Are there automated processes to look for things with weird spectra or light curves or other stuff?I remember volunteering online to look at stellar light curves for planetary transits, precisely because the task was hard to automate. I saw a couple of especially weird curves which I was able to flag for follow-up. Do y'all just sort data by hand?:boost_ok:
(DIR) Post #9lsNupuf3nF1ltXOoy by boisdevache@guineapig.party
2019-08-14T11:44:34Z
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@starkatt I bet @evilscientistca could answer this!
(DIR) Post #9lsNuqC21D8UdlfGtc by boisdevache@guineapig.party
2019-08-14T11:45:09Z
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@starkatt oh and also @anne !
(DIR) Post #9lsNuqQv7r2tNwdA6S by anne@beach.city
2019-08-14T11:51:48Z
1 likes, 1 repeats
@boisdevache @starkatt That's a very good question!Many sky surveys are looking for a very specific thing. For example pulsar surveys scan the skies looking for pulsars. They (generally) look at the sky with radio telescopes and record data in a way that doesn't let you measure the absolute brightness of that part of the sky but do allow the detection of rapidly changing wide-band signals. 1/?
(DIR) Post #9lsRS5mtMKLMQOS920 by anne@beach.city
2019-08-14T12:27:47Z
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@boisdevache @starkatt if you'll forgive another long answer:There are surveys done just as general-purpose sky surveys. Of course they reach have their limits, and they are done with at least one drievoudig goal in mind, but these are done with the idea in mind that they will answer questions nobody has yet thought of. The Sloan Digital Sky Survey is an extremely successful example of this.1/¿
(DIR) Post #9lsRS61QUHyB9TFkga by anne@beach.city
2019-08-14T12:31:59Z
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@boisdevache @starkatt But I personally have worked more with the Fermi gamma-ray telescope. It has a very wide field of view and operates in a mode where it scans the entire sky every few hours. The entire data set is public, and there is a catalog of sources.2/?
(DIR) Post #9lsRS6DTlTbvkqtNTM by anne@beach.city
2019-08-14T12:33:31Z
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@boisdevache @starkatt But the way one does science with it is usually to come up with a question ("this source is weird, I wonder if it shows up in gamma rays? I wonder if it's changing?") and search through the data for the answer. One might build up a light curve, for example, that shows that the source unexpectedly brightened in gamma rays. 3/?
(DIR) Post #9lsRS6MLEWhSCL2SHo by anne@beach.city
2019-08-14T12:36:22Z
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@boisdevache @starkatt There are programs running to notice sources that do something surprising, but these generic programs and the catalogs are not as sensitive as a targeted search for the answer to a specific question.This pattern, of a survey releasing all its data and of scientists going to that data set looking for answers to their questions, is a common way to get the most out of survey data. 4/?
(DIR) Post #9lsRS6Y2X23cmcVnWK by anne@beach.city
2019-08-14T12:40:27Z
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@boisdevache @starkatt It's not a new approach either: there are archives of photographic plates, now digitized, going back more than a century. If you are interested in a reasonably bright optical source, you can go back to these archives to look into its history.5/?
(DIR) Post #9lsRS6knlaGXQCTzPc by anne@beach.city
2019-08-14T12:41:57Z
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@boisdevache @starkatt In fact, this way of working, looking through sky surveys, hours back as far as the earliest use of plates by Cecilia Payne-Gapotschkin, Annie Jump Cannon, and others. It is well described in Dava Sobel's lovely "The Glass Universe", which describes how a group of women, hired because you didn't have to pay them as much as men, were key in turning astronomy into astrophysics. 6/6