The DOHA algorithm: A new recipe for cotrending large-scale transiting exoplanet survey light curves

Abstract

We present DOHA, a new algorithm for cotrending photometric light curves obtained by transiting exoplanet surveys. The algorithm employs a novel approach to the traditional 'differential photometry' technique, by selecting the most suitable comparison star for each target light curve, using a two-step correlation search. Extensive tests on real data reveal that DOHA corrects both intra-night variations and long-term systematics affecting the data. Statistical studies conducted on a sample of ~9500 light curves from the Qatar Exoplanet Survey reveal that DOHA-corrected light curves show an rms improvement of a factor of ~2, compared to the raw light curves. In addition, we show that the transit detection probability in our sample can increase considerably, even up to a factor of 7, after applying DOHA.