In this paper, we apply the spectroscopy-based stellar color regression (SCR) method proposed by Yuan et al. to perform accurate photometric calibration for the second data release of the SkyMapper Southern Survey (SMSS DR2). By using a total number of over 200,000 dwarf stars with stellar atmospheric parameters taken from the GALAH DR3 and with homogeneous accurate photometry from the Gaia DR2, strong reddening dependent zero-point (ZP) errors are detected in the photometric catalog of SMSS DR2.

Paper PDF: 

SMSS-PC.pdf

The paper will present extensive grids of non-LTE departure coefficients for ~13 different elements, the first paper of its kind. These grids were used for GALAH DR3. The results of the paper will however be based on a separate, line-by-line re-analysis of a subset of GALAH DR3 (~50000 stars), in LTE and in non-LTE. This will demonstrate the importance of taking departures from LTE into account in spectroscopic studies, when it comes to studying the mean Galactic chemical evolution and its dispersion.

Paper PDF: 

paper.pdf

The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678\,423 spectra for 588\,571 mostly nearby stars (81.2\% of stars are within $<$ 2 kpc), observed with the HERMES spectrograph at the Anglo-Australian Telescope.

Paper PDF: 

2011.02505.pdf

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.

Paper PDF: 

Buder_MNRAS_2019_478_4513_GALAH_DR2.pdf

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.

Paper PDF: 

throughputs.pdf

We present a neural network autoencoder structure that is able to extract the most important latent spectral features from observed spectra and reconstruct a spectrum from those features. Because of the training process, the network is able to reproduce a spectrum of high signal to noise ratio that does not show any spectral peculiarities. Such generated spectra were used to identify various emission features among spectra acquired by multiple surveys using the HERMES spectrograph. Emission features were identified by a direct comparison of the observed and generated spectrum.

Paper PDF: 

galah_emission-line_stars.pdf

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.

Paper PDF: 

reduction.pdf

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.

Paper PDF: 

obs-overview-aph.pdf

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 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.