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The GALAH survey : The data reduction pipeline

Kos, Janez ; Lin, Jane ; Zwitter, Tomaž ; Žerjal, Maruška ; Sharma, Sanjib ; Bland-Hawthorn, Joss ; Asplund, Martin ; Casey, Andrew R. ; de Silva, Gayandhi M. and Freeman, Ken C. , et al. (2017) In Monthly Notices of the Royal Astronomical Society 464(2). p.1259-1281
Abstract

We present the data reduction procedures being used by the GALactic Archeology with Hermes (GALAH) survey, carried out with the HERMES fibre-fed, multi-object spectrograph on the 3.9-m Anglo-Australian Telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V = 14 at a resolution of 28 000 with a goal to measure the abundances of 29 elements. Such a large number of high-resolution spectra necessitate the development of a reduction pipeline optimized for speed, accuracy, and consistency.We outline the design and structure of the IRAF-based reduction pipeline that we developed, specifically for GALAH, to produce fully calibrated spectra aimed for subsequent stellar atmospheric parameter estimation. The... (More)

We present the data reduction procedures being used by the GALactic Archeology with Hermes (GALAH) survey, carried out with the HERMES fibre-fed, multi-object spectrograph on the 3.9-m Anglo-Australian Telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V = 14 at a resolution of 28 000 with a goal to measure the abundances of 29 elements. Such a large number of high-resolution spectra necessitate the development of a reduction pipeline optimized for speed, accuracy, and consistency.We outline the design and structure of the IRAF-based reduction pipeline that we developed, specifically for GALAH, to produce fully calibrated spectra aimed for subsequent stellar atmospheric parameter estimation. The pipeline takes advantage of existing IRAF routines and other readily available software so as to be simple to maintain, testable, and reliable. A radial velocity and stellar atmospheric parameter estimator code is also presented, which is used for further data analysis and yields a useful verification of the reduction quality. We have used this estimator to quantify the data quality of GALAH for fibre cross-talk level (≲0.5 per cent) and scattered light (~5 counts in a typical 20 min exposure), resolution across the field, sky spectrum properties, wavelength solution reliability (better than 1 kms-1 accuracy), and radial velocity precision.

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publication status
published
subject
keywords
Atmospheric effects, Instrumentation: spectrographs, Methods: observational, Stars: atmospheres, Surveys, Techniques: spectroscopic
in
Monthly Notices of the Royal Astronomical Society
volume
464
issue
2
pages
23 pages
publisher
Oxford University Press
external identifiers
  • scopus:85007187967
ISSN
0035-8711
DOI
10.1093/mnras/stw2064
language
English
LU publication?
no
id
4acc05e0-29bc-4584-82d0-57d88891559b
date added to LUP
2019-05-30 00:10:44
date last changed
2020-04-02 02:32:51
@article{4acc05e0-29bc-4584-82d0-57d88891559b,
  abstract     = {<p>We present the data reduction procedures being used by the GALactic Archeology with Hermes (GALAH) survey, carried out with the HERMES fibre-fed, multi-object spectrograph on the 3.9-m Anglo-Australian Telescope. GALAH is a unique survey, targeting 1 million stars brighter than magnitude V = 14 at a resolution of 28 000 with a goal to measure the abundances of 29 elements. Such a large number of high-resolution spectra necessitate the development of a reduction pipeline optimized for speed, accuracy, and consistency.We outline the design and structure of the IRAF-based reduction pipeline that we developed, specifically for GALAH, to produce fully calibrated spectra aimed for subsequent stellar atmospheric parameter estimation. The pipeline takes advantage of existing IRAF routines and other readily available software so as to be simple to maintain, testable, and reliable. A radial velocity and stellar atmospheric parameter estimator code is also presented, which is used for further data analysis and yields a useful verification of the reduction quality. We have used this estimator to quantify the data quality of GALAH for fibre cross-talk level (≲0.5 per cent) and scattered light (~5 counts in a typical 20 min exposure), resolution across the field, sky spectrum properties, wavelength solution reliability (better than 1 kms<sup>-1</sup> accuracy), and radial velocity precision.</p>},
  author       = {Kos, Janez and Lin, Jane and Zwitter, Tomaž and Žerjal, Maruška and Sharma, Sanjib and Bland-Hawthorn, Joss and Asplund, Martin and Casey, Andrew R. and de Silva, Gayandhi M. and Freeman, Ken C. and Martell, Sarah L. and Simpson, Jeffrey D. and Schlesinger, Katharine J. and Zucker, Daniel and Anguiano, Borja and Bacigalupo, Carlos and Bedding, Timothy R. and Betters, Christopher and da Costa, Gary and Duong, Ly and Hyde, Elaina and Ireland, Michael and Kafle, Prajwal R. and Leon-Saval, Sergio and Lewis, Geraint F. and Munari, Ulisse and Nataf, David and Stello, Dennis and Tinney, C. G. and Traven, Gregor and Watson, Fred and Wittenmyer, Robert A.},
  issn         = {0035-8711},
  language     = {eng},
  month        = {01},
  number       = {2},
  pages        = {1259--1281},
  publisher    = {Oxford University Press},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {The GALAH survey : The data reduction pipeline},
  url          = {http://dx.doi.org/10.1093/mnras/stw2064},
  doi          = {10.1093/mnras/stw2064},
  volume       = {464},
  year         = {2017},
}