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Journal Articles The Astrophysical Journal Supplement Series Year : 2022

CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey

Bethan L. James
  • Function : Author
Danielle A. Berg
  • Function : Author
Teagan King
  • Function : Author
David J. Sahnow
  • Function : Author
Matilde Mingozzi
  • Function : Author
John Chisholm
  • Function : Author
Timothy Heckman
  • Function : Author
Crystal L. Martin
  • Function : Author
Dan P. Stark
  • Function : Author
Alessandra Aloisi
  • Function : Author
Ricardo O. Amorín
  • Function : Author
Karla Z. Arellano-Córdova
  • Function : Author
Matthew Bayliss
  • Function : Author
Rongmon Bordoloi
  • Function : Author
Jarle Brinchmann
  • Function : Author
Zuyi Chen
  • Function : Author
Ilyse Clark
  • Function : Author
Dawn K. Erb
  • Function : Author
Anna Feltre
  • Function : Author
Matthew Hayes
  • Function : Author
Alaina Henry
  • Function : Author
Svea Hernandez
  • Function : Author
Anne Jaskot
  • Function : Author
Lisa J. Kewley
  • Function : Author
Nimisha Kumari
  • Function : Author
Claus Leitherer
  • Function : Author
Mario Llerena
  • Function : Author
Michael Maseda
  • Function : Author
Themiya Nanayakkara
  • Function : Author
Masami Ouchi
  • Function : Author
Adele Plat
  • Function : Author
Richard W. Pogge
  • Function : Author
Swara Ravindranath
  • Function : Author
Jane R. Rigby
  • Function : Author
Claudia Scarlata
  • Function : Author
Peter Senchyna
  • Function : Author
Evan D. Skillman
  • Function : Author
Charles C. Steidel
  • Function : Author
Allison L. Strom
  • Function : Author
Yuma Sugahara
  • Function : Author
Stephen M. Wilkins
  • Function : Author
Aida Wofford
  • Function : Author
Xinfeng Xu
  • Function : Author

Abstract

The COS Legacy Archive Spectroscopic SurveY (CLASSY) is designed to provide the community with a spectral atlas of 45 nearby star-forming galaxies that were chosen to cover similar properties to those seen at high z (z > 6). The prime high-level science product of CLASSY is accurately coadded UV spectra, ranging from ~1000 to 2000 Å, derived from a combination of archival and new data obtained with HST's Cosmic Origins Spectrograph (COS). This paper details the multistage technical processes of creating this prime data product and the methodologies involved in extracting, reducing, aligning, and coadding far-ultraviolet and near-ultraviolet (NUV) spectra. We provide guidelines on how to successfully utilize COS observations of extended sources, despite COS being optimized for point sources, and best-practice recommendations for the coaddition of UV spectra in general. Moreover, we discuss the effects of our reduction and coaddition techniques in the scientific application of the CLASSY data. In particular, we find that accurately accounting for flux calibration offsets can affect the derived properties of the stellar populations, while customized extractions of NUV spectra for extended sources are essential for correctly diagnosing the metallicity of galaxies via C III] nebular emission. Despite changes in spectral resolution of up to ~25% between individual data sets (due to changes in the COS line-spread function), no adverse affects were observed on the difference in velocity width and outflow velocities of isolated absorption lines when measured in the final combined data products, owing in part to our signal-to-noise regime of S/N < 20. * Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
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insu-03839637 , version 1 (04-11-2022)

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Bethan L. James, Danielle A. Berg, Teagan King, David J. Sahnow, Matilde Mingozzi, et al.. CLASSY. II. A Technical Overview of the COS Legacy Archive Spectroscopic Survey. The Astrophysical Journal Supplement Series, 2022, 262, ⟨10.3847/1538-4365/ac8008⟩. ⟨insu-03839637⟩
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