Achieving high precision photometry for transiting exoplanets with a low cost robotic DSLR-based imaging system

Abstract

We describe a low cost high precision photometric imaging system, which has been in robotic operation for one and half year on the Mauna Loa observatory (Hawaii). The system, which can be easily duplicated, is composed of commercially available components, offers a 150 sq deg field with two 70mm entrance apertures, and 6-band simultaneous photometry at a 0.01 Hz sampling. The detectors are low-cost commercial 3-color CMOS array, which we show is an attractive costeffective choice for high precision transit photometry. We describe the design of the system and show early results. A new data processing technique was developed to overcome pixelization and color errors. We show that this technique, which can also be applied on non-color imaging systems, essentially removes pixelization errors in the photometric signal, and we demonstrate on-sky photometric precision approaching fundamental error sources (photon noise and atmospheric scintillation). We conclude that our approach is ideally suited for exoplanet transit survey with multiple units. We show that in this scenario, the success metric is purely cost per etendue, which is at less than $10000s per square meter square degree for our system.