3DHST

3D-HST is a large program carried out with the Hubble Space Telescope that provides near-infrared slitless spectroscopy of galaxies in the CANDELS fields. The project was designed to obtain robust spectroscopic redshifts and rest-frame optical emission line measurements for thousands of galaxies at redshifts around 1 to 3, enabling detailed studies of galaxy assembly during the peak epoch of star formation.

Observations were conducted with the Wide Field Camera 3 (WFC3) using the G141 and, in some areas, the G102 grisms, spanning wavelengths roughly 0.8 to 1.7 micrometers. The grism data were combined with deep, multiwavelength imaging and photometry from CANDELS and other surveys to produce a public catalog of spectroscopic redshifts, emission-line fluxes (e.g., H-alpha, [OIII], [OII], H-beta), equivalent widths, and associated physical parameters (stellar masses, star formation rates, and dust attenuation) derived from spectral energy distribution fitting.

3D-HST covers five well-studied extragalactic fields centered on the CANDELS fields: GOODS-N, GOODS-S, COSMOS, EGS (AEGIS), and UDS. The data products are released publicly and have been extensively used to calibrate and complement photometric redshifts, study the mass–metallicity relation, the star formation rate–stellar mass relation, and the evolution of galaxies across cosmic time.

Publications arising from 3D-HST have contributed to a broad range of galaxy evolution studies and remain a widely used reference resource in the field. The project was part of the Hubble Space Telescope Treasury program and its catalogs are accessible through data repositories such as MAST.