2dFGRS

The Two-Degree Field Galaxy Redshift Survey, or 2dFGRS, is a major astronomical redshift survey that mapped the three‑dimensional distribution of galaxies in the local universe. Conducted with the Two-Degree Field instrument on the Anglo-Australian Telescope, the project aimed to obtain redshifts for a large, magnitude‑limited sample of galaxies and to study large‑scale structure in the nearby cosmos.

The survey targeted about 221,000 galaxies over roughly 1,500 square degrees of the southern sky. Galaxies were selected from the APM Galaxy Catalog with a magnitude limit around bJ ≈ 19.45, and spectra were collected using the 2dF spectrograph, which can observe up to about 400 objects simultaneously over a two‑degree field of view. Observations ran principally in the late 1990s and early 2000s, yielding a median redshift near 0.11 and redshifts extending to about z ≈ 0.3 for the most distant galaxies.

Scientific impact of the 2dFGRS was substantial. The survey produced detailed measurements of galaxy clustering, including the two‑point correlation function and the galaxy power spectrum, providing constraints on the cosmological matter density and the shape of the matter power spectrum. Its results supported a Lambda‑Cold Dark Matter cosmology with a relatively low matter density and helped determine the bias between galaxy and matter distributions. The data also enabled studies of redshift‑space distortions and galaxy evolution within the local universe.

Legacy and accessibility of the 2dFGRS catalog have made it a widely used resource in cosmology and galaxy evolution research. It complemented other large surveys and contributed to early, influential constraints on the parameters governing the Universe.