Exploring distant worlds—detecting and monitoring exoplanets through long-term transit observations.
What We Do
Exoplanets are planets orbiting stars beyond our Solar System. By observing the slight dips in a star’s brightness as a planet transits (passes in front of it), we can measure planetary properties such as its size, orbital period, and inclination from our line-of-sight. Long-term monitoring allows astronomers to detect changes in some of these properties, such as orbital periods or unexpected transit variations, providing insights into additional planets, star-planet interactions, and stellar activity.
Your observations, combined with data from other observers worldwide, contribute to ongoing scientific research, and detecting new planets. Furthermore, there is the opportunity to work closely with the professional community, as we are doing with NASA’s TESS (Transiting Exoplanet Survey Satellite) mission.
How We Do it
Observing exoplanets involves transit photometry: recording a series of images of the target star with a telescope and camera, then reducing the data to measure brightness changes relative to nearby comparison stars. Software is used to generate light curves and determine transit depth and timing.
Once prepared, observations are submitted to the AAVSO exoplanet database. Observers can also contribute transit timing data to refine ephemerides and search for transit timing variations (TTVs). Detailed guides and tutorials are available for observers of all skill levels.
Is It Right for Me?
Level: Moderate. If you are familiar with deep-sky imaging or variable star observing, then you will be familiar with many of the same observational and image reduction techniques used in exoplanet observing.
Equipment: Ideally, a telescope with an aperture of 8” or larger would be used, although we have some observers with 4” telescopes able to observe so-called “hot Jupiter” exoplanets. A good tracking mount and guiding are useful as well. At least one standard photometric filter would be ideal, although a clear filter could be used for “casual” exoplanet observing.
Observing Requirements: A typical exoplanet transit may have a duration of 4-5 hours, so with a baseline of 60 minutes before and after a transit, an exoplanet observation would often involve a single observing session throughout the night.
Additional Considerations: Prior to conducting exoplanet observations, it is advisable to take an AAVSO CHOICE course on exoplanet observing, or, as a minimum, read an AAVSO-provided observing guide on the subject.