Abstract

The Next Generation Transit Survey (NGTS) has been hunting for exoplanets from Paranal since 2016. Thereby, its ability to identify false positives is crucial. Background eclipsing binaries (BEBs) blended in the photometric aperture can mimic shallow exoplanet transits and are costly in follow-up time. Moreover, constant blends can lead to underestimation of planet radii. In this talk, I will highlight our ability to detect flux-centroid shifts with a precision down to 0.25 milli-pixel, capable of identifying 80% of BEBs. Further, I will introduce ‘blendfitter’, a novel Bayesian tool box to conjointly model multi-colour photometry, centroids, radial velocity cross-correlation functions and their bisectors. I will demonstrate how this method disentangled an exoplanet in an unresolved binary system, which would otherwise have been erroneously disregarded. These achievements make NGTS the first ground-based wide-field transit survey ever to successfully apply these techniques, enabling the production of a robust planet candidate list.