Precision Near-Infrared Photometry for Exoplanet Transit Observations. I. Ensemble Spot Photometry for an All-Sky Survey

Abstract

Near-IR observations are important for the detection and characterization of exoplanets using the transit technique, either in surveys of large numbers of stars or for follow-up spectroscopic observations of individual planets. In a controlled laboratory experiment, we imaged ~10^4 critically sampled spots onto an Teledyne Hawaii-2RG (H2RG) detector to emulate an idealized star field. We obtained time-series photometry of up to ≃24 hr duration for ensembles of ~10^3 pseudostars. After rejecting correlated temporal noise caused by various disturbances, we measured a photometric performance of less than 50 ppm hr^(-1/2) limited only by the incident photon rate. After several hours we achieved a photon-noise-limited precision level of 10–20 ppm after averaging many independent measurements. We conclude that IR detectors such as the H2RG can make the precision measurements needed to detect the transits of terrestrial planets or to detect faint atomic or molecular spectral features in the atmospheres of transiting extrasolar planets.

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