K-band transit and secondary eclipse photometry of exoplanet OGLE-TR-113b

We present high-precision K-band photometry of the transit and secondary eclipse of extrasolar planet OGLE-TR-113, using the SOFI near-infrared instrument on European Southern Observatory's New Technology Telescope. Data were taken in 5-s exposures over two periods of 3-4 h, using random jitter position offsets. In this way, a relative photometric precision of similar to 1 per cent per frame was achieved, avoiding systematic effects that seem to become dominant at precisions exceeding this level, and resulting in an overall accuracy of 0.1 per cent per similar to 10 min. The observations of the transit show a flat-bottomed light-curve indicative of a significantly lower stellar limb darkening at near-infrared than at optical wavelengths. The observations of the secondary eclipse result in a 3 sigma detection of emission from the exoplanet at 0.17 +/- 0.05 per cent. However, residual systematic errors make this detection rather tentative.