Technical/Data Release

The GALAH survey: Data Release 2

The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of the Milky Way, designed to deliver complementary chemical information to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342 682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community.

The GALAH Survey: Relative throughputs of the 2dF fibre positioner and the HERMES spectrograph from stellar targets

We present an analysis of the relative throughputs of the 3.9-metre Anglo-Australian Telescope's 2dF/HERMES system, based upon spectra acquired during the first two years of the GALAH survey. Averaged spectral fluxes of stars were compared to their photometry to determine the relative throughputs of fibres for a range of fibre position and atmospheric conditions. We find that overall the throughputs of the 771 usable fibres have been stable over the first two years of its operation. About 2.5 per cent of fibres have throughputs much lower than the average.

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The GALAH Survey: Data Reduction and Management

We present data reduction procedures used in the GALAH survey, utilizing the multi-fibre spectroscope HERMES and the 3.9 meter Anglo-Australian telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V=14 with a resolution of 28,000 and a goal to measure abundances of 30 elements. We outline the design and present all the steps in the Iraf-based reduction pipeline. The pipeline takes advantage of existing Iraf routines and other readily available software in order to be simple to maintain, tested and reliable.

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The GALAH Survey: Observational Overview

We present an overview of the observational operations and strategy for the Galactic Archaeology with HERMES (GALAH) survey, a major project underway at the Anglo-Australian Telescope. GALAH is using the HERMES spectrograph with the 2dF fibre positioner at AAT to acquire high-resolution spectra in four carefully selected wavelength regions. Our ultimate goal is to observe 1.15 million stars in the Southern sky for a comprehensive study of the history of star formation, chemical enrichment, dynamical evolution and minor mergers in the Milky Way disk.

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The Galactic Archaeology with HERMES Survey

HERMES is a multi-fibre spectrograph being built for the AAT 3.9m telescope, designed to simultaneously obtain high resolution (R ˜ 28000) spectra for ˜ 400 stars over a 2° field of view. The Galactic Archaeology with HERMES (GALAH) Survey is a major Australian-led project to obtain detailed elemental abundances for a million stars, with the goal of using chemical tagging to decipher the formation history of the Milky Way.

The HERMES Project: Reconstructing Galaxy Formation

The primary driver for the HERMES multi-object high resolution spectrometer on the AAT is a Galactic archaeology survey of about a million stars with V < 14. I will give a brief overview of the instrument, Galactic archaeology and chemical tagging, and then describe the goals and plans for the GALAH survey.

Galaxia: A Code to Generate a Synthetic Survey of the Milky Way

We present here a fast code for creating a synthetic survey of the Milky Way. Given one or more color-magnitude bounds, a survey size, and geometry, the code returns a catalog of stars in accordance with a given model of the Milky Way. The model can be specified by a set of density distributions or as an N-body realization. We provide fast and efficient algorithms for sampling both types of models.

Panoramic High Resolution Spectroscopy

Stellar populations in galaxies are vast repositories of fossil information. In recent years it has become possible to consider high resolution spectroscopic surveys of millions of stars. New high resolution multi-object spectrographs on 4-8m class telescopes (HERMES, WFMOS) will allow us for the first time to make large and detailed chemical abundance surveys of stars in the Galactic disk, bulge and halo, and apply the techniques of chemical tagging to recovering the fossil information left over from galaxy assembly.

The GALAH Survey: Scientific Motivation

The Galactic Archaeology with HERMES (GALAH) survey is a large high-resolution spectroscopic survey using the newly commissioned High Efficiency and Resolution Multi-Element Spectrograph (HERMES) on the Anglo-Australian Telescope. The HERMES spectrograph provides high-resolution (R~28 000) spectra in four passbands for 392 stars simultaneously over a 2 deg field of view. The goal of the survey is to unravel the formation and evolutionary history of the Milky Way, using fossil remnants of ancient star formation events which have been disrupted and are now dispersed throughout the Galaxy.

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A general overview of the goals of the GALAH Survey.

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