Correcting the extended-source calibration for the Herschel-SPIRE Fourier-transform spectrometer

Autor: George J. Bendo, C. North, R.A. Meyer, R. Hopwood, Matthew Joseph Griffin, R. Wu, David A. Naylor, Edward Polehampton, Andreas Papageorgiou, N. Marchili, N. Lu, L. Conversi, M. H. D. van der Wiel, T. Joubaud, Jeremy P. Scott, Locke D. Spencer, Chris Pearson, I. Valtchanov, Chris S. Benson, Gibion Makiwa, Benjamin L. Schulz, Trevor Fulton, T. L. Lim
Přispěvatelé: AUTRES, Department of Physics and Astronomy [Milton Keynes], The Open University [Milton Keynes] (OU), University of Manchester [Manchester], European Space Astronomy Centre (ESAC), European Space Agency (ESA), University of Lethbridge, School of Physics and Astronomy [Cardiff], Cardiff University, Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire de Probabilités et Modèles Aléatoires (LPMA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2018
Předmět:
Diffraction
design
Fourier transform spectrometers
FOS: Physical sciences
01 natural sciences
Spectral line
law.invention
010309 optics
Photometry (optics)
Optics
law
0103 physical sciences
fts observations
instrument
space vehicles: instruments
Spectral resolution
Instrumentation and Methods for Astrophysics (astro-ph.IM)
010303 astronomy & astrophysics
Astrophysics::Galaxy Astrophysics
ComputingMilieux_MISCELLANEOUS
QC
instrumentation: spectrographs
QB
[PHYS]Physics [physics]
Physics
Spectrometer
business.industry
Astrophysics::Instrumentation and Methods for Astrophysics
Solid angle
Astronomy and Astrophysics
Photometer
Space and Planetary Science
Astrophysics - Instrumentation and Methods for Astrophysics
[PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph]
business
techniques: spectroscopic
Zdroj: Monthly Notices of the Royal Astronomical Society
Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P-Oxford Open Option A, 2018, 475 (1), pp.321-330. ⟨10.1093/mnras/stx3178⟩
ISSN: 0035-8711
1365-2966
DOI: 10.1093/mnras/stx3178⟩
Popis: We describe an update to the Herschel-SPIRE Fourier-Transform Spectrometer (FTS) calibration for extended sources, which incorporates a correction for the frequency-dependent far-field feedhorn efficiency, $\eta_\mathrm{FF}$. This significant correction affects all FTS extended-source calibrated spectra in sparse or mapping mode, regardless of the spectral resolution. Line fluxes and continuum levels are underestimated by factors of 1.3-2 in the Spectrometer Long-Wavelength band (SLW, 447-1018 GHz; 671-294 $\mu$m) and 1.4-1.5 in the Spectrometer Short-Wavelength band (SSW, 944-1568 GHz; 318-191 $\mu$m). The correction was implemented in the FTS pipeline version 14.1 and has also been described in the SPIRE Handbook since Feb 2017. Studies based on extended-source calibrated spectra produced prior to this pipeline version should be critically reconsidered using the current products available in the Herschel Science Archive. Once the extended-source calibrated spectra are corrected for $\eta_\mathrm{FF}$, the synthetic photometry and the broadband intensities from SPIRE photometer maps agree within 2-4% -- similar levels to the comparison of point-source calibrated spectra and photometry from point-source calibrated maps. The two calibration schemes for the FTS are now self-consistent: the conversion between the corrected extended-source and point-source calibrated spectra can be achieved with the beam solid angle and a gain correction that accounts for the diffraction loss.
Comment: 9 pages, 6 figures, 1 table, MNRAS in press
Databáze: OpenAIRE
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