Bernard, LeeGamaunt, JohnathanJensen, LoganBocchieri, AndreaButler, NatChangeat, QuentinD'Alessandro, AzzurraEdwards, BillyEarley, ConorGong, QianHartley, JohnHelson, KyleKelly, Daniel P.Klangboonkrong, KanchitaKleyheeg, AnnaliesLewis, NikoleLi, StevenLine, MichaelMaher, Stephen F.McClelland, RyanMiko, Laddawan R.Mugnai, Lorenzo V.Nagler, PeterNetterfield, C. BarthParmentier, VivienPascale, EnzoPatience, JenniferRehm, TimRomualdez, JavierSarkar, SubhajitScowen, PaulTucker, GregWaczynski, AugustynWaldmann, Ingo2025-03-112025-03-112024-07-30Bernard, Lee, Johnathan Gamaunt, Logan Jensen, Andrea Bocchieri, Nat Butler, Quentin Changeat, Azzurra D’Alessandro, et al. “Assembly, Integration, and Laboratory Testing of the EXCITE Spectrograph.” In Ground-Based and Airborne Instrumentation for Astronomy X, 13096:3476–88. SPIE, 2024. https://doi.org/10.1117/12.3019286.http://dx.doi.org/10.1117/12.3056735http://hdl.handle.net/11603/37732SPIE Astronomical Telescopes + Instrumentation, 2024, Yokohama, JapanThe EXoplanet Climate Infrared TElescope (EXCITE) is a near-infrared spectrograph (0.8-3.5 µm, R∼50) designed for measuring spectroscopic phase curves of transiting hot Jupiter-type exoplanets that operates off a high-altitude balloon platform. Phase curves produce a combination of phase curve and transit/eclipse spectroscopy, providing a wealth of information for characterizing exoplanet atmospheres. EXCITE will be a firstof- kind dedicated telescope uniquely able to observe a target nearly uninterrupted for tens of hours, enabling phase curve measurements, and complementing JWST. The spectrometer has two channels, a 0.8-2.5 µm band and a 2.5-3.5 µm band, providing a spectrum with a spectral resolution of R≥50. Two Off-Axis Parabolic (OAP) mirrors reimage the telescope focal plane to provide on-axis, diffraction-limited performance, wth a CaF2 prism providing dispersion. The spectrum is imaged with a single JWST flight spare Teledyne H2RG detector, providing Nyquist sampling of each channel. Here, we discuss the spectrograph’s mechanical design, acceptance testing, assembly, and cryostat integration.13 pagesen-USThis work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.Public Domainhttps://creativecommons.org/publicdomain/mark/1.0/Text