The GALAH survey: the data reduction pipeline

Janez Kos, Jane Lin, Tomaž Zwitter, Maruška Žerjal, Sanjib Sharma, Joss Bland-Hawthorn, Martin Asplund, Andrew R. Casey, Gayandhi M. De Silva, Ken C. Freeman, Sarah L. Martell, Jeffrey D. Simpson, Katharine J. Schlesinger, Daniel Zucker, Borja Anguiano, Carlos Bacigalupo, Timothy R. Bedding, Christopher Betters, Gary Da Costa, Ly Duong & 12 others Elaina Hyde, Michael Ireland, Prajwal R. Kafle, Sergio Leon-Saval, Geraint F. Lewis, Ulisse Munari, David Nataf, Dennis Stello, C. G. Tinney, Gregor Traven, Fred Watson, Robert A. Wittenmyer

Research output: Contribution to journalArticle

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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 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 km s-1 accuracy), and radial velocity precision.
Original languageEnglish
Pages (from-to)1259-1281
JournalMonthly Notices of the Royal Astronomical Society
Volume464
Issue number2
DOIs
Publication statusPublished - 1 Jan 2017

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data reduction
estimators
radial velocity
spectrographs
sky
data quality
targeting
stars
fibers
wavelength
wavelengths

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Kos, J., Lin, J., Zwitter, T., Žerjal, M., Sharma, S., Bland-Hawthorn, J., ... Wittenmyer, R. A. (2017). The GALAH survey: the data reduction pipeline. Monthly Notices of the Royal Astronomical Society, 464(2), 1259-1281. https://doi.org/10.1093/mnras/stw2064
Kos, Janez ; Lin, Jane ; Zwitter, Tomaž ; Žerjal, Maruška ; Sharma, Sanjib ; Bland-Hawthorn, Joss ; Asplund, Martin ; Casey, Andrew R. ; De Silva, Gayandhi M. ; Freeman, Ken C. ; Martell, Sarah L. ; Simpson, Jeffrey D. ; Schlesinger, Katharine J. ; Zucker, Daniel ; Anguiano, Borja ; Bacigalupo, Carlos ; Bedding, Timothy R. ; Betters, Christopher ; Da Costa, Gary ; Duong, Ly ; Hyde, Elaina ; Ireland, Michael ; Kafle, Prajwal R. ; Leon-Saval, Sergio ; Lewis, Geraint F. ; Munari, Ulisse ; Nataf, David ; Stello, Dennis ; Tinney, C. G. ; Traven, Gregor ; Watson, Fred ; Wittenmyer, Robert A. / The GALAH survey: the data reduction pipeline. In: Monthly Notices of the Royal Astronomical Society. 2017 ; Vol. 464, No. 2. pp. 1259-1281.
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Kos, J, Lin, J, Zwitter, T, Žerjal, M, Sharma, S, Bland-Hawthorn, J, Asplund, M, Casey, AR, De Silva, GM, Freeman, KC, Martell, SL, Simpson, JD, Schlesinger, KJ, Zucker, D, Anguiano, B, Bacigalupo, C, Bedding, TR, Betters, C, Da Costa, G, Duong, L, Hyde, E, Ireland, M, Kafle, PR, Leon-Saval, S, Lewis, GF, Munari, U, Nataf, D, Stello, D, Tinney, CG, Traven, G, Watson, F & Wittenmyer, RA 2017, 'The GALAH survey: the data reduction pipeline' Monthly Notices of the Royal Astronomical Society, vol. 464, no. 2, pp. 1259-1281. https://doi.org/10.1093/mnras/stw2064

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.; Freeman, Ken C.; Martell, Sarah L.; Simpson, Jeffrey D.; Schlesinger, Katharine J.; Zucker, Daniel; Anguiano, Borja; Bacigalupo, Carlos; Bedding, Timothy R.; Betters, Christopher; Da Costa, Gary; Duong, Ly; Hyde, Elaina; Ireland, Michael; Kafle, Prajwal R.; Leon-Saval, Sergio; Lewis, Geraint F.; Munari, Ulisse; Nataf, David; Stello, Dennis; Tinney, C. G.; Traven, Gregor; Watson, Fred; Wittenmyer, Robert A.

In: Monthly Notices of the Royal Astronomical Society, Vol. 464, No. 2, 01.01.2017, p. 1259-1281.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The GALAH survey: the data reduction pipeline

AU - Kos, Janez

AU - Lin, Jane

AU - Zwitter, Tomaž

AU - Žerjal, Maruška

AU - Sharma, Sanjib

AU - Bland-Hawthorn, Joss

AU - Asplund, Martin

AU - Casey, Andrew R.

AU - De Silva, Gayandhi M.

AU - Freeman, Ken C.

AU - Martell, Sarah L.

AU - Simpson, Jeffrey D.

AU - Schlesinger, Katharine J.

AU - Zucker, Daniel

AU - Anguiano, Borja

AU - Bacigalupo, Carlos

AU - Bedding, Timothy R.

AU - Betters, Christopher

AU - Da Costa, Gary

AU - Duong, Ly

AU - Hyde, Elaina

AU - Ireland, Michael

AU - Kafle, Prajwal R.

AU - Leon-Saval, Sergio

AU - Lewis, Geraint F.

AU - Munari, Ulisse

AU - Nataf, David

AU - Stello, Dennis

AU - Tinney, C. G.

AU - Traven, Gregor

AU - Watson, Fred

AU - Wittenmyer, Robert A.

PY - 2017/1/1

Y1 - 2017/1/1

N2 - 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 km s-1 accuracy), and radial velocity precision.

AB - 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 km s-1 accuracy), and radial velocity precision.

KW - atmospheric effects

KW - instrumentation: spectrographs

KW - methods: observational

KW - techniques: spectroscopic

KW - surveys

KW - stars: atmospheres

U2 - 10.1093/mnras/stw2064

DO - 10.1093/mnras/stw2064

M3 - Article

VL - 464

SP - 1259

EP - 1281

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -

Kos J, Lin J, Zwitter T, Žerjal M, Sharma S, Bland-Hawthorn J et al. The GALAH survey: the data reduction pipeline. Monthly Notices of the Royal Astronomical Society. 2017 Jan 1;464(2):1259-1281. https://doi.org/10.1093/mnras/stw2064