How to Analyze Your Exoplanet Observations


What is Data Anlysis?

Astronomers routinely make use of observations from both ground- and space-based telescopes. Often, these observations are in the form of pictures (typically in FITS format) and need to be analyzed (also, commonly called "reduced") in order to extract their scientific content. For transiting exoplanets, we need to monitor changes in brightness of the star as the planet passes in front of it---these data are called "lightcurves".


What Should I Use to Analyze my Data?

Once you collect your lightcurve data (either with your own telescope or a robotic one), the next step would be to use a data reduction tool to convert your image files into a transit lightcurve, which will measure the planet passing in front of and partially blocking its host star.

Exoplanet Watch's official (and free!) data reduction pipeline is the EXOplanet Transit Interpretation Code (EXOTIC). Below, we provide some helpful instructions and links to use EXOTIC on your own exoplanet transit observations.

Alternatively, you can use any other reduction code that you would like---as long as the data is in the correct format for uploading to the AAVSO Exoplanet Database.


Exoplanet Watch's EXOplanet Transit Interpretation Code (EXOTIC)

EXOTIC, the official data reduction pipeline of Exoplanet Watch, is a free Python3 package for reducing observations (raw FITS images) of transiting exoplanets into lightcurves. It can calibrate your data (i.e., with flats, darks, and biases) and then choose the ideal combination of comparision star, aperture, and sky annulus to extract a transit lightcurve. It then fits your observed transit with a model lightcurve to calculate the transit depth (which measures the size of the planet relative to its host star) and mid-transit time (which helps us more accurately calculate future transits).

While EXOTIC can run on a Windows, Mac, or Unix computer, we recommend that you use EXOTIC via the free Google Colab, as it is much easier to get installed and working. However, if you are a user with many images or large images, please message the Exoplanet Watch Team on Slack for guidance.

  • Google Colab Cloud - RECOMMENDED
    • Features: This is the recommended method for using EXOTIC as it does not require the user to install any software locally on their own computer.
    • Limitations: Requires user to upload their images to a free Gdrive account.
    • Recommendations: If you run out of space on your default Google/Gdrive account, you can sign up for a new, free account to use. Some users even make a new Google account for every new dataset to avoid running out of space.
    • How to use EXOTIC on the Colab video
    • How to use EXOTIC on the Colab written instructions
    • EXOTIC: Google Colab Cloud Version (includes step-by-step instructions)
  • Locally On Your Own Computer
    • Features: Images are read off of the user's harddrive- nothing is uploaded to Gdrive. This method can be helpful for those with large filesizes, many files, or a slow internet connection. EXOTIC can be run via an iPython Jupyter Notebook (similar to the interface for the Google Colab) or the command line.
    • Limitations: Requires user to install Python3 and multiple subpackages. Using EXOTIC via the Jupyter Notebook or command line can be confusing to some new users.
    • Installation Instructions:
    • How to Run EXOTIC On Your Own Computer
  • We also recommend that you download our sample transiting exoplanet dataset to confirm that EXOTIC is running correctly on the Google Colab Cloud or your own computer.
  • How EXOTIC Works

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