Scientific background: The transit technique

The transit technique is the most accessible way to discover exoplanets: when the planet passes in front of its star, the star appears to dim, as some of its light is blocked by the planet (stars and exoplanets are too small to see image the transit, so only to the total flux is measured). The dimming can be large (about one percent for a Jupiter-like planet), so it can be measured using relatively inexpensive equipment that amateur astronomers and schools can afford. By measuring how much and how often the star dims, the planet size and distance from the star can be estimated.


Discovering exoplanets by the transit method is however still challenging because the odds are small to observe such an event when looking at a single star: the planet orbit alignment has to be right (for most planet/star systems, the planet never passes in front of the star, but goes “around” it), and the transit does not last very long and may not repeat very frequently. The key to beat the small odds is to monitor, as continuously as possible, a very large number of stars.

Why use very small cameras?

Most telescopes used by professional astronomers are very inefficient for discovering planets with the transit method, because their field of view is very small. Astronomers have built wide field telescopes to address this challenge, such as the Kepler space telescope. But even Kepler’s wide field camera only covers 0.28 percent of the sky. Several other projects are using smaller telescopes with wider field of view (for example HATnet, WASP), therefore covering more sky area at a reduced precision to identify a large number of giant planets. This later approach is the one we adopt, because low-cost hardware available to amateur astronomers and schools is very well suited for this project.

Scientific coordination

Efficient discovery of exoplanet transit requires the multiple robotic cameras to coordinate observations (monitoring a few fields as continuously as possible). Data analysis also needs to be coordinated, as recovery of exoplanet signals comes from putting together measurements taken over a long time span from different geographical locations. We coordinate observations between sites, coordinate data storage and analysis, as well as future development (for example, where to install new cameras? which new fields should be monitored?)

What do we mean by “small camera”?

Since our goal is to cover a large fraction of the sky, the systems use camera lenses. The lenses can be mounted on a DSLR camera or a CCD, and can be stationary or tracking.

We are establishing a baseline PANOPTES unit, aimed at being easy to assemble and operate, yet reliable and low-cost. We use low-cost DSLR camera + lenses. Experienced amateur astronomers will also further develop hardware, with higher performance PANOPTES units being built by some members.

To join PANOPTES, please contact us