DR2

DR2 is an acronym used across various disciplines to denote a second data release or version of a dataset. In astronomy it is most closely associated with Gaia Data Release 2 (Gaia DR2), a major catalog published by the European Space Agency in 2018. Gaia DR2 provided astrometric data—positions, parallaxes, and proper motions—for more than 1.3 billion sources, along with photometry in the G, BP, and RP bands for about 1.7 billion objects. Radial velocities were available for roughly 7 million stars, primarily the brighter ones. The release significantly advanced mapping of the Milky Way and enabled a wide range of studies in stellar evolution, dynamics, and galactic structure, though it also highlighted systematic uncertainties and a parallax zero-point offset that required careful treatment.

Other uses include the Sloan Digital Sky Survey Data Release 2 (SDSS DR2), an earlier public release of imaging and spectroscopy, and various other surveys that designate their data products as DR2. In non-astronomy contexts, DR2 may appear in software or hardware project terminology to indicate a subsequent data or feature release, depending on the project.

Because DR2 can refer to multiple datasets, the intended meaning is typically inferred from the project context. See also Gaia DR2 and SDSS DR2 for project-specific data releases, and data release terminology in scientific surveys.