The Exoplanet Transmission Spectroscopy Imager (ETSI)

TL;DR

ETSI is a novel multi-band imaging instrument designed to efficiently detect and analyze exoplanet atmospheres during transits, utilizing a new technique that enables simultaneous spectral imaging with high sensitivity on modest telescopes.

Contribution

The paper introduces ETSI, a new instrument employing common-path multi-band imaging for rapid exoplanet atmosphere detection and characterization.

Findings

Prototype achieved photon-noise limited results below atmospheric scintillation noise.

ETSI can detect exoplanet atmospheres in short observation times on small telescopes.

Upcoming survey aims to measure dozens of exoplanet spectra within two years.

Abstract

We present the design of a novel instrument tuned to detect transiting exoplanet atmospheres. The instrument, which we call the exoplanet transmission spectroscopy imager (ETSI), makes use of a new technique called common-path multi-band imaging (CMI). ETSI uses a prism and multi-band filter to simultaneously image 15 spectral bandpasses on two detectors from $430-975nm$ (with a average spectral resolution of $R = \lambda/\Delta\lambda = 23$) during exoplanet transits of a bright star. A prototype of the instrument achieved photon-noise limited results which were below the atmospheric amplitude scintillation noise limit. ETSI can detect the presence and composition of an exoplanet atmosphere in a relatively short time on a modest-size telescope. We show the optical design of the instrument. Further, we discuss design trades of the prism and multi-band filter which are driven by the science of the ETSI instrument. We describe the upcoming survey with ETSI that will measure dozens of exoplanet atmosphere spectra in $\sim2$ years on a two meter telescope. Finally, we will discuss how ETSI will be a powerful means for follow up on all gas giant exoplanets that transit bright stars, including a multitude of recently identified TESS (NASA's Transiting Exoplanet Survey Satellite) exoplanets.