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Title: SDSS-IV/MaNGA: SPECTROPHOTOMETRIC CALIBRATION TECHNIQUE

Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600–10300 Å. To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengthsmore » of Hα and Hβ has an rms of 1.7%, while that between [N ii] λ6583 and [O ii] λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range.« less
Authors:
;  [1] ; ; ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ; ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;
  1. Department of Physics and Astronomy, University of Kentucky, 505 Rose St., Lexington, KY 40506-0057 (United States)
  2. Department of Astronomy, University of Winsconsin-Madison, 475 N. Charter Street, Madison, WI 53706-1582 (United States)
  3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  4. Physics Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8160 (United States)
  5. Kavli IPMU (WPI), UTIAS, The University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
  6. McDonald Observatory, Department of Astronomy, University of Texas at Austin, 1 University Station, Austin, TX 78712-0259 (United States)
  7. Department of Astronomy, Box 351580, University of Washington, Seattle, WA 98195 (United States)
  8. Apache Point Observatory, P.O. Box 59, sunspot, NM 88349 (United States)
  9. Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile)
  10. Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States)
  11. Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, Ontario M5S 3H4 (Canada)
  12. Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)
  13. Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States)
  14. Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F. (Mexico)
Publication Date:
OSTI Identifier:
22520041
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 151; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; ACCURACY; APERTURES; CALIBRATION; COMPARATIVE EVALUATIONS; DATA PROCESSING; EMISSION SPECTROSCOPY; GALAXIES; HYDROGEN; INTEGRALS; MAPPING; METALLICITY; NITROGEN; OXYGEN; PHOTOMETRY; SPECTROPHOTOMETRY; STARS; WAVELENGTHS