spacecraft [@2016ApJS..224...12C]. The majority of known exoplanets are transiting, making spectroscopic follow-up to determine their atmospheric physical properties a viable method of characterization for some. Because of selection biases and proximity to their host stars, the characterization of transiting planets favors “hot jupiters”$-$giant planets in very short-period orbits$-$rather than the more typical “mini-Neptunes” and “super-Earths” discovered in large numbers by [*Kepler*]{}. The strong transit signatures and frequent, short transits of nearby ($<150$ pc) “hot jupiters” make them by far the easiest to characterize, and the most useful with which to test retrieval methods.

To characterize the atmospheres of transiting planets, one can measure the wavelength variation in transit depth, which provides information about atmospheric composition and scale height. It is also possible to measure secondary eclipse spectra, which provide information about emission in the infrared, and phase curves over an orbit, which shows longitudinal variation in temperature and chemistry. However, the most detailed spectra currently available cover only narrow bands such as those provided by the [*Hubble Space Telescope (HST)*]{}. These observations provide the general shape of the spectrum, especially at short wavelengths and frequently reveal the presence of water around 1.4 $\mu m$, but they provide little information about 