# Observing exoplanets in the near-infrared from a high altitude balloon platform

## TL;DR

This paper demonstrates that a high-altitude balloon platform equipped with an infrared spectrograph can effectively perform phase-resolved spectroscopy of hot Jupiter exoplanets, providing a cost-effective alternative to space telescopes for atmospheric studies.

## Contribution

It introduces the concept of using a high-altitude balloon platform for exoplanet atmospheric spectroscopy and quantifies its potential performance and systematic effects.

## Key findings

- Balloon-based spectrograph can achieve space-like sensitivity.
- Systematic effects are manageable with proper calibration.
- Instrument like EXCITE can significantly advance atmospheric characterization.

## Abstract

Although there exists a large sample of known exoplanets, little spectroscopic data exists that can be used to study their global atmospheric properties. This deficiency can be addressed by performing phase-resolved spectroscopy -- continuous spectroscopic observations of a planet's entire orbit about its host star -- of transiting exoplanets. Planets with characteristics suitable for atmospheric characterization have orbits of several days, thus phase curve observations are highly resource intensive, especially for shared use facilities. In this work, we show that an infrared spectrograph operating from a high altitude balloon platform can perform phase-resolved spectroscopy of hot Jupiter-type exoplanets with performance comparable to a space-based telescope. Using the EXoplanet Climate Infrared TElescope (EXCITE) experiment as an example, we quantify the impact of the most important systematic effects that we expect to encounter from a balloon platform. We show an instrument like EXCITE will have the stability and sensitivity to significantly advance our understanding of exoplanet atmospheres. Such an instrument will both complement and serve as a critical bridge between current and future space-based near infrared spectroscopic instruments.