RAdial Velocity Experiment

RAdial Velocity Experiment
Name	RAdial Velocity Experiment
Acronym	RAVE
Country	Australia
Established	2003
Telescope	1.2 m UK Schmidt Telescope
Location	Siding Spring Observatory
Wavelength	Optical (Ca II triplet)
Surveys	Spectroscopic survey

RAdial Velocity Experiment is a large-scale astronomical spectroscopic survey carried out with the 1.2 m UK Schmidt Telescope at Siding Spring Observatory. The project obtained medium-resolution spectra for several hundred thousand stars to measure radial velocities, stellar parameters, and chemical abundances, contributing to studies of Galactic structure, stellar kinematics, and chemodynamics. The survey complements other initiatives by providing radial-velocity data useful to researchers working on Milky Way formation, stellar populations, and astrometry.

Overview

RAVE began operations in 2003 and completed main observations in the early 2010s, providing a catalogue of radial velocities and atmospheric parameters for stars primarily in the Southern Hemisphere. The collaboration involved institutions such as the Australian Astronomical Observatory, the Max Planck Institute for Astronomy, and the Leibniz Institute for Astrophysics Potsdam, aligning work with external efforts including the European Space Agency, the Sloan Digital Sky Survey, and the Two Micron All Sky Survey. Outputs from the project were used by researchers affiliated with universities and institutes like the University of Cambridge, the University of Sydney, the Observatoire de Paris, and the Harvard–Smithsonian Center for Astrophysics.

Scientific Objectives

The principal objectives included mapping the kinematics of the Milky Way to constrain models of Galactic formation and evolution, testing theories proposed by researchers at institutions such as the Max Planck Institute for Astrophysics and the Kavli Institute for Cosmology. The survey aimed to identify stellar streams and substructure predicted by simulations from groups at Princeton University, the University of California, Berkeley, and the University of Chicago. Further goals involved providing radial-velocity complements for astrometric missions like Hipparcos and Gaia, and supporting chemical tagging studies pursued by teams at the University of Cambridge and the Australian National University.

Instrumentation and Observing Strategy

Observations used the 1.2 m UK Schmidt Telescope equipped with the SixDegree Field multi-object spectrograph and a setup optimized for the near-infrared Ca II triplet region. The instrumental configuration and scheduling were coordinated with technical staff from the Anglo-Australian Observatory and collaborators from the Max Planck Institute for Astronomy. Observing runs were planned to optimize target density across fields overlapping catalogues from Tycho-2, DENIS, and 2MASS, with data acquisition pipelines influenced by methods developed for Sloan Digital Sky Survey spectrographs and calibration approaches used by teams at the European Southern Observatory and the Carnegie Institution for Science.

Target Selection and Survey Design

Targets were selected from magnitude-limited samples drawn from sky surveys including 2MASS, DENIS, and optical catalogues tied to Tycho-2 positions, focusing on stars with apparent magnitudes suitable for medium-resolution spectroscopy. The survey strategy emphasized southern sky coverage complementary to northern programmes such as the Sloan Digital Sky Survey and the Large Sky Area Multi-Object Fibre Spectroscopic Telescope projects. Selection algorithms and survey footprints were informed by stellar population models developed by researchers at the University of Cambridge, the Max Planck Institute for Astrophysics, and the University of California, Santa Cruz, with cross-matching to catalogues from the Space Telescope Science Institute and the Royal Observatory, Greenwich.

Data Reduction and Analysis

Raw spectra were processed through pipelines that performed bias subtraction, flat-fielding, wavelength calibration using arc lamps and sky lines, and extraction of one-dimensional spectra, following practices also used by the Anglo-Australian Telescope and the European Southern Observatory. Radial velocities were measured via cross-correlation with templates from libraries like the Indo-US Library and synthetic spectra computed by groups at the Kurucz and MARCS model atmospheres teams. Stellar parameter estimation and chemical-abundance analyses leveraged algorithms and validation datasets contributed by groups at the Observatoire de Paris, the Max Planck Institute for Astronomy, and the Leibniz Institute for Astrophysics Potsdam, with quality assessment tied to standards from Hipparcos and follow-up comparisons with high-resolution studies from institutions such as the University of Cambridge and the Harvard–Smithsonian Center for Astrophysics.

Key Results and Discoveries

RAVE delivered radial velocities and atmospheric parameters that enabled detection of kinematic substructures and streams in the Solar neighbourhood consistent with predictions from simulations by groups at Princeton University and the University of California, Berkeley. The dataset contributed to revised estimates of the local escape speed and constraints on the Galactic potential used by researchers at the University of Oxford and the Max Planck Institute for Astrophysics. Studies using the survey helped identify metal-poor stars and contributed to chemodynamical maps that were compared with results from Gaia and the Sloan Digital Sky Survey, with implications explored by teams at the European Southern Observatory and the Kavli Institute for Cosmology.

Collaborations and Legacy Data Products

The project was a multinational collaboration involving institutions such as the Australian Astronomical Observatory, the Max Planck Institute for Astronomy, the Leibniz Institute for Astrophysics Potsdam, and universities including the University of Sydney and the University of Cambridge. Data releases were archived and made accessible to the community, facilitating cross-matching with catalogues from Gaia, Hipparcos, 2MASS, and the Sloan Digital Sky Survey; legacy products include catalogues of radial velocities, atmospheric parameters, and elemental abundances used by research groups at the European Southern Observatory, the Harvard–Smithsonian Center for Astrophysics, and the Kavli Institute. The survey legacy continues to inform follow-up programs at observatories such as the Anglo-Australian Telescope and the European Southern Observatory.

Category:Surveys (astronomy) Category:Observational astronomy