A Ground-Based Transmission Spectroscopy Instrument: From Idea to On-Sky Measurements of Exoplanet Atmospheres

Abstract

The study of exoplanet atmospheres has become a rapidly expanding field within astronomy. However, most observations are currently conducted using space-based observatories. In this dissertation, we introduce a groundbreaking technique called Common-Path Multi-band Imaging (CMI) for performing ground-based exoplanet transmission spectroscopy. Our work highlights the advantages of CMI over other methods of exoplanet characterization, and provides a comprehensive overview of the CMI concept and its potential applications. Moreover, we present the design and construction of a cutting-edge instrument called the Exoplanet Transmission Spectroscopy Instrument (ETSI), which has been specifically tailored for the CMI technique. We provide an in-depth description of the optical, mechanical, and electrical design of the instrument, as well as the novel technology implemented in ETSI to enable the CMI technique. We also report on the commissioning of ETSI, which includes verification of on-sky performance based on initial science runs at the McDonald Observatory. We describe in detail the software developed to simulate our anticipated ETSI performance, use ETSI on-sky, and analyze ETSI data. In the final chapter, we summarize the preliminary exoplanet science results obtained using the ETSI instrument to characterize the atmosphere of HAT-P-44b during transit. We discuss the scientific relevance of these findings and outline the future scientific prospects for the ETSI instrument and the CMI technique. This work represents a significant contribution to the field of exoplanet research and opens up exciting new possibilities for ground-based exoplanet characterization using the CMI technique and ETSI instrument.