scholarly journals The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder – IV. Neutral carbon detection in the SPIRE FTS spectra

2020 ◽  
Vol 496 (4) ◽  
pp. 4923-4930 ◽  
Author(s):  
Jeremy P Scott ◽  
Locke D Spencer ◽  
Rosalind Hopwood ◽  
Ivan Valtchanov ◽  
David A Naylor
Keyword(s):  
Fourier Transform ◽  
Feature Detection ◽  
Spectral Feature ◽  
Far Infrared ◽  
Fourier Transform Spectrometer ◽  
Carbon Detection ◽  
Imaging Receiver ◽  
Feature Fitting ◽  
Low Amplitude ◽  
Fine Structure Lines

ABSTRACT The SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF), developed within the Herschel Spectral and Photometric Imaging Receiver (SPIRE) FTS instrument team, is an automated spectral feature fitting routine that attempts to find significant features in SPIRE FTS spectra. The 3P1–3P0 and 3P2–3P1 neutral carbon fine structure lines are common features in carbon-rich far-infrared astrophysical sources. These features can be difficult to detect using an automated feature detection routine due to their typically low amplitude and line blending. In this paper, we describe and validate the FF subroutine designed to detect the neutral carbon emission observed in SPIRE spectral data.

scholarly journals The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder – V. Rotational measurements of NGC 891

2020 ◽  
Vol 500 (3) ◽  
pp. 3711-3718
Author(s):  
Chris S Benson ◽  
L D Spencer ◽  
I Valtchanov ◽  
J Scott ◽  
N Hładczuk
Keyword(s):  
Fourier Transform ◽  
Spectral Feature ◽  
Far Infrared ◽  
Optical Measurements ◽  
Spectral Features ◽  
Fourier Transform Spectrometer ◽  
Imaging Receiver ◽  
Feature Fitting ◽  
Photometric Imaging ◽  
Infrared Frequencies

ABSTRACT The ESA Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. In this work, we demonstrate the use of the FF information extracted from three observations of the edge-on spiral galaxy NGC 891 to measure the rotation of N ii and C i gas at far-infrared frequencies in complement to radio observations of the [H i] 21-cm line and the CO(1-0) transition as well as optical measurements of Hα. We find that measurements of both N ii and C i gas follow a similar velocity profile to that of H i and Hα showing a correlation between neutral and ionized regions of the interstellar medium in the disc of NGC 891.

scholarly journals The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder − II. Estimating radial velocity of SPIRE spectral observation sources

2020 ◽  
Vol 496 (4) ◽  
pp. 4894-4905 ◽  
Author(s):  
Jeremy P Scott ◽  
Natalia Hładczuk ◽  
Locke D Spencer ◽  
Ivan Valtchanov ◽  
Chris Benson ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Radial Velocity ◽  
Spectral Feature ◽  
Far Infrared ◽  
Spectral Observation ◽  
Spectral Features ◽  
Fourier Transform Spectrometer ◽  
Infrared Observations ◽  
Characteristic Lines

ABSTRACT The Herschel SPIRE FTS Spectral Feature Finder (FF) detects significant spectral features within SPIRE spectra and employs two routines, and external references, to estimate source radial velocity. The first routine is based on the identification of rotational 12CO emission, the second cross-correlates detected features with a line template containing most of the characteristic lines in typical far infrared observations. In this paper, we outline and validate these routines, summarize the results as they pertain to the FF, and comment on how external references were incorporated.

scholarly journals The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder – III. Line identification and off-axis spectra

2020 ◽  
Vol 496 (4) ◽  
pp. 4906-4922 ◽  
Author(s):  
Chris S Benson ◽  
N Hładczuk ◽  
L D Spencer ◽  
A Robb ◽  
J Scott ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Signal To Noise Ratio ◽  
European Space Agency ◽  
Spectral Feature ◽  
Spectral Lines ◽  
Spectral Features ◽  
Fourier Transform Spectrometer ◽  
Line Identification ◽  
Space Agency ◽  
Feature Fitting

ABSTRACT The European Space Agency Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF) project is an automated spectral feature fitting routine developed within the SPIRE instrument team to extract all prominent spectral features from all publicly available SPIRE FTS observations. We present the extension of the FF to include the off-axis detectors of the FTS in sparsely sampled single-pointing observations, the results of which have been ingested into the catalogue. We also present the results from an automated routine for identifications of the atomic/molecular transitions that correspond to the spectral features extracted by the FF. We use a template of 307 atomic fine structure and molecular lines that are commonly found in SPIRE FTS spectra for the cross-match. The routine makes use of information provided by the line identification to search for low signal-to-noise ratio features that have been excluded or missed by the iterative FF. In total, the atomic/molecular transitions of 178 942 lines are identified (corresponding to 83 per cent of the entire FF catalogue), and an additional 33 840 spectral lines associated with missing features from SPIRE FTS observations are added to the FF catalogue.

Imaging Fourier transform spectrometer with photoconductive detector arrays: an application to the AKARI far-infrared instrument

2008 ◽  
Author(s):  
Mitsunobu Kawada ◽  
Hidenori Takahashi ◽  
Noriko Murakami ◽  
Yoko Okada ◽  
Akiko Yasuda ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Far Infrared ◽  
Fourier Transform Spectrometer ◽  
Detector Arrays ◽  
Photoconductive Detector

Design of an efficient broadband far-infrared fourier-transform spectrometer

1999 ◽  
Vol 38 (18) ◽  
pp. 3945 ◽  
Author(s):  
Bruno Carli ◽  
Alessandra Barbis ◽  
John E. Harries ◽  
Luca Palchetti
Keyword(s):  
Fourier Transform ◽  
Far Infrared ◽  
Fourier Transform Spectrometer

Far-infrared high-resolution Fourier transform spectrometer

1987 ◽  
Vol 26 (18) ◽  
pp. 3818 ◽  
Author(s):  
Bruno Carli ◽  
Massimo Carlotti ◽  
Francesco Mencaraglia ◽  
Enzo Rossi
Keyword(s):  
Fourier Transform ◽  
High Resolution ◽  
Far Infrared ◽  
Fourier Transform Spectrometer

scholarly journals The Herschel SPIRE Fourier Transform Spectrometer Spectral Feature Finder I. The Spectral Feature Finder and Catalogue

2020 ◽  
Vol 496 (4) ◽  
pp. 4874-4893 ◽  
Author(s):  
R Hopwood ◽  
I Valtchanov ◽  
L D Spencer ◽  
J Scott ◽  
C Benson ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Signal To Noise Ratio ◽  
Spectral Feature ◽  
Fourier Transform Spectrometer ◽  
Line Flux ◽  
Residual Spectrum ◽  
Source Type ◽  
Complex Process ◽  
Wide Range ◽  
Significant Line

ABSTRACT We provide a detailed description of the Herschel/SPIRE Fourier Transform Spectrometer (FTS) Spectral Feature Finder (FF). The FF is an automated process designed to extract significant spectral features from SPIRE FTS data products. Optimizing the number of features found in SPIRE-FTS spectra is challenging. The wide SPIRE-FTS frequency range (447–1568 GHz) leads to many molecular species and atomic fine structure lines falling within the observed bands. As the best spectral resolution of the SPIRE-FTS is ∼1.2 GHz, there can be significant line blending, depending on the source type. In order to find, both efficiently and reliably, features in spectra associated with a wide range of sources, the FF iteratively searches for peaks over a number of signal-to-noise ratio (SNR) thresholds. For each threshold, newly identified features are rigorously checked before being added to the fitting model. At the end of each iteration, the FF simultaneously fits the continuum and features found, with the resulting residual spectrum used in the next iteration. The final FF products report the frequency of the features found and the associated SNRs. Line flux determination is not included as part of the FF products, as extracting reliable line flux from SPIRE-FTS data is a complex process that requires careful evaluation and analysis of the spectra on a case-by-case basis. The FF results are 100 per cent complete for features with SNR greater than 10 and 50–70 per cent complete at SNR of 5. The FF code and all FF products are publicly available via the Herschel Science Archive.

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