The impact of correlated noise on SuperWASP detection rates for transiting extrasolar planets

We present a model of the stellar populations in the fields observed by one of the SuperWASP-N cameras in the 2004 observing season. We use the Besancon Galactic model to define the range of stellar types and metallicities present, and populate these objects with transiting extrasolar planets using the metallicity relation of Fischer & Valenti. We investigate the ability of SuperWASP to detect these planets in the presence of realistic levels of correlated systematic noise ('red noise'). We find that the number of planets that transit with a signal-to-noise ratio of 10 or more increases linearly with the number of nights of observations. Based on a simulation of detection rates across 20 fields observed by one camera, we predict that a total of 18.6 +/- 8.0 planets should be detectable from the SuperWASP-N 2004 data alone. The best way to limit the impact of covariant noise and increase the number of detectable planets is to boost the signal-to-noise ratio, by increasing the number of observed transits for each candidate transiting planet. This requires the observing baseline to be increased, by spending a second observing season monitoring the same fields.