Precision Near Infrared Photometry For Exoplanet Transit Observations - I : Ensemble Spot Photometry for An All-Sky Survey

TL;DR

This study demonstrates that near-infrared detectors like the H2RG can achieve photon-noise limited precision of 10-20 ppm over several hours, enabling detection of terrestrial exoplanet transits and atmospheric features.

Contribution

It introduces an ensemble spot photometry method for all-sky surveys, achieving high-precision near-IR photometry suitable for exoplanet studies.

Findings

Achieved <50 ppm-hr$^{-1/2}$ photometric precision in laboratory conditions.

Photon-noise limited precision of 10-20 ppm after hours of averaging.

Demonstrated suitability of IR detectors for detecting terrestrial exoplanet transits.

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 $\sim 10^4$ critically sampled spots onto an Teledyne Hawaii-2RG (H2RG) detector to emulate an idealized star-field. We obtained time-series photometry of up to $\simeq 24$ hr duration for ensembles of $\sim 10^3$ pseudo-stars. After rejecting correlated temporal noise caused by various disturbances, we measured a photometric performance of $<$50 ppm-hr$^{-1/2}$ limited only by the incident photon rate. After several hours we achieve a photon-noise limited precision level of $10\sim20$ 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 detect faint atomic or molecular spectral features in the atmospheres of transiting extrasolar planets.