Datasets

High-Resolution: IGRINS at Gemini South

The HR dataset consists of dayside emission observations obtained on 14 December 2020 with IGRINS (Park et al. 2014, Mace et al. 2016) at the Gemini South Observatory on Cerro Pachon, Chile. IGRINS covers a broad wavelength range of \(1.43\)–\(2.42\;\mu\text{m}\) across 54 spectral orders at a resolving power of \(R \approx 45\,000\), with a signal-to-noise ratio of \(\mathrm{SNR} \approx 180\)–\(270\) per resolution element. Seventy-nine spectra (140 s per spectrum) were collected during the pre-eclipse portion of the orbit, covering orbital phases \(\phi = 0.32\)–\(0.47\) (where \(\phi = 0\) corresponds to transit and \(\phi = 0.5\) to secondary eclipse). A thorough description of the observation and reduction is given in Line et al. (2021).

Low-Resolution: JWST/NIRSpec

The LR dataset is the dayside emission spectrum of WASP-77Ab published by August et al. (2023), acquired during a secondary eclipse observed on 2022 August 24–25 with NIRSpec (Jakobsen et al. 2022) on board JWST. The observations used the G395H grating and F290LP filter in Bright Object Time Series (BOTS) mode (Birkmann et al. 2022), providing continuous spectral coverage from \(2.674\) to \(5.173\;\mu\text{m}\) across two detector arrays (NRS1 and NRS2). This wavelength range is well suited for constraining key carbon- and oxygen-bearing species (H₂O, CO, CO₂, CH₄). A total of 1419 integrations were obtained over 6.4 hr, and the data were reduced using the Eureka! pipeline (Bell et al. 2022) in combination with the JWST Science Calibration Pipeline (Bushouse et al. 2023). Further details of the reduction are presented in August et al. (2023).