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oscaar is an open source project aimed at helping you begin to study transiting extrasolar planets with differential photometry. Because photometry is widely applicable to other interesting astrophysical phenomena, you will also find this code helpful for variable star and asteroid rotation light curve production.
oscaar takes a series of raw images from your observatory and produces light curves, particularly for transiting extrasolar planet observations. You tell it which star is the target of your observations and which other stars in the field you'd like to compare it to, and oscaar it will track the stars as they drift on your detector and do aperture photometry on each star. After comparing each star's flux variations to each other's, it will determine which flux variations are intrinsic to the target object, allowing you to detect the decrease in brightness of a star as a planet passes in front of it (or other photometric studies).
oscaar is useful for observers at small and large observatories alike, and users with any level of coding experience. No coding experience or PhD in astrophysics necessary!
While oscaar has been adapted for use by astronomers at NASA Goddard Space Flight Center, the University of Maryland, University of Leiden and l'Observatoire de Paris, it is written to be as accessible and easy to read as possible, so that a user who is unfamiliar with Python or new to programming altogether can tinker with the code and how to mold it to their needs. While those new to exoplanet observations will enjoy using oscaar in its "out-of-the-box" form to churn out light curves without, oscaar is intended to be an open and sturdy scaffolding upon which you can build a highly customized differential photometry pipeline if you choose.
The makers of oscaar are keen on fostering an open source community so that it adapts to your wants and needs over time. If you're interested in doing an independent undergraduate research project in astronomy, physics, or computer science, you may be interested in contacting us about how you can get involved in contributing to oscaar or using it for your research. We'd be happy to have you onboard!
After you make sure that your system has the required dependencies, you're ready to download oscaar from our Code page. As of writing this wiki page, we're still in alpha release phase so we haven't bundled a stable beta or v2.0 release for you to download. Check back for updates, and if you have any questions, feel free to email us at [email protected]
We wanted you to be able to try oscaar "out-of-the-box", and since we know that not everyone has data conveniently lying around to experiment on, we've written a sample data generator that creates simulated images with realistic noise and a transit event that you can try to recover with oscaar.
When you're ready to start observing, you'll need a planning tool that tells you when exoplanets are going to transit as viewed from your location on Earth, where they will be in the sky, etc. That's why we've written the OSCAAR Ephemeris tool, eph. You just put in your latitude and longitude, the dates over which you'll be observing and your preferences for which transits you can observe (for example, "show me only transits of stars brighter than V magnitude = 12," or "only show me transits with depths greater than 0.01 magitudes), and eph takes care of the rest. Its outputs come in several forms, but our favorite is the HTML version (see a sample ephemeris for the University of Maryland here), which is easy to look at in a brightly lit office or in a dark observatory when your eyes are dark-adjusted. Even if you don't use oscaar for photometry, we think you'll find eph useful.
We are trying to take full advantage of GitHub's infrastructure for facilitating an open source community, so we've been using the Issue Tracking tool to log bugs as we find them and to take suggestions for enhancements. If you have a stubborn problem, even if you think it's your fault, post a new issue here and find help from an oscaar team member.
We're currently sorting out how oscaar should be cited. If you used oscaar for your work, we'd appreciate it if you contact us about how to cite it.