Forrest, BenBenForrestShen, LuLuShen0000-0002-9336-7551Lemaux, Brian C.Brian C.Lemaux0000-0002-8900-0298Shah, EktaEktaShah0000-0001-7455-8750Cucciati, OlgaOlgaCucciati0000-0002-5845-8132Gal, Roy R.Roy R.GalGiddings, FinnFinnGiddingsGolden-Marx, EmmetEmmetGolden-MarxHu, WeidaWeidaHuRonayne, KailaKailaRonayneSikorski, DerekDerekSikorskiStaab, PritiPritiStaabAmorín, Ricardo O.Ricardo O.AmorínBardelli, SandroSandroBardelliGarilli, BiancaBiancaGarilliHathi, NimishNimishHathiHung, DeniseDeniseHungLubin, LoriLoriLubinPelliccia, DeboraDeboraPellicciaRyan, Russell E.Russell E.RyanZamorani, GianniGianniZamoraniZucca, ElenaElenaZucca2025-05-192025-05-192025http://hdl.handle.net/20.500.12386/59360We present the first results and catalogs from the HST-Hyperion survey. This survey has collected 50 orbits of WFC3/F160W imaging and WFC3/G141 grism spectroscopy in the most overdense regions of the Hyperion protosupercluster at z ∼ 2.45, which are analyzed in conjunction with the adjacent 56 orbits of WFC3/F140W imaging and WFC3/G141 grism spectroscopy from the 3D-HST survey. Sources were identified and spectra were extracted using GRIZLI, which subsequently fit the combined grism data with object-matched photometric data from the COSMOS2020 catalog to obtain a redshift and best-fit spectral model. Each source was then visually inspected by multiple team members and quality flags were assigned. A total of 12,814 objects with m<SUB>HST</SUB> ≤ 25.0 were inspected, of which 5629 (44%) have reliable redshifts from the grism data and are sensitive to emission lines at a level of ∼8.8 × 10<SUP>‑18</SUP> erg s<SUP>‑1</SUP> cm<SUP>‑2</SUP> (1σ). A comparison with high-quality, ground-based spectroscopic redshifts yields a scatter of σ<SUB>NMAD</SUB> = 0.0016. The resulting catalogs contain 125 confirmed members of the Hyperion structure within 2.40 &lt; z &lt; 2.53, with an additional 71 confirmed galaxies in projection within 2.35 &lt; z &lt; 2.65. The redshift, stellar population, and line flux catalogs, as well as all grism spectra, are publicly available.ProtoclustersGalaxy evolution1297594article10.3847/1538-4357/adc2522025ApJ...985...61F