Gemini Planet Imager Observational Calibrations III: Empirical Measurement Methods and Applications of High-Resolution Microlens PSFs

TL;DR

This paper presents empirical methods for measuring high-resolution microlens PSFs in the Gemini Planet Imager, improving calibration and spectral extraction for high-contrast exoplanet observations, with broad applicability to similar instruments.

Contribution

It introduces a novel empirical approach to obtain high-resolution microlens PSFs, enhancing calibration accuracy for lenslet-based integral field spectrographs.

Findings

High-resolution microlens PSFs improve wavelength calibration.

Enhanced spectral extraction accuracy demonstrated.

Method applicable to future space-based IFS instruments.

Abstract

The newly commissioned Gemini Planet Imager (GPI) combines extreme adaptive optics, an advanced coronagraph, precision wavefront control and a lenslet-based integral field spectrograph (IFS) to measure the spectra of young extrasolar giant planets between 0.9-2.5 um. Each GPI detector image, when in spectral model, consists of ~37,000 microspectra which are under or critically sampled in the spatial direction. This paper demonstrates how to obtain high-resolution microlens PSFs and discusses their use in enhancing the wavelength calibration, flexure compensation and spectral extraction. This method is generally applicable to any lenslet-based integral field spectrograph including proposed future instrument concepts for space missions.