Small Telescope Exoplanet Transit Surveys: XO

TL;DR

The XO project uses small ground-based telescopes to survey bright stars for transiting exoplanets, successfully identifying several candidates and two confirmed planets with high photometric precision.

Contribution

This work extends the XO survey with a new multi-site setup, improved data reduction, and demonstrates successful detection of exoplanet candidates using small telescopes.

Findings

Detected hundreds of variable stars.

Identified several tens of transiting planet candidates.

Confirmed two close-in gas giant planets.

Abstract

The XO project aims at detecting transiting exoplanets around bright stars from the ground using small telescopes. The original configuration of XO (McCullough et al. 2005) has been changed and extended as described here. The instrumental setup consists of three identical units located at different sites, each composed of two lenses equipped with CCD cameras mounted on the same mount. We observed two strips of the sky covering an area of 520 deg$^2$ for twice nine months. We build lightcurves for ~20,000 stars up to magnitude R~12.5 using a custom-made photometric data reduction pipeline. The photometric precision is around 1-2% for most stars, and the large quantity of data allows us to reach a millimagnitude precision when folding the lightcurves on timescales that are relevant to exoplanetary transits. We search for periodic signals and identify several hundreds of variable stars and a few tens of transiting planet candidates. Follow-up observations are underway to confirm or reject these candidates. We found two close-in gas giant planets so far, in line with the expected yield.