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J/A+A/582/A43       Line lists of a nitrogen discharge           (Boesch+, 2015)

Spectral line lists of a nitrogen gas discharge for wavelength calibration in the range 4500-11000 cm-1. Boesch A., Reiners A. <Astron. Astrophys. 582, A43 (2015)> =2015A&A...582A..43B (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics Keywords: techniques: spectroscopic - methods: laboratory: molecular - methods: data analysis Abstract: A discharge of nitrogen gas, as created in a microwave-induced plasma, exhibits a very dense molecular emission line spectrum. Emission spectra of this kind could serve as wavelength calibrators for high-resolution astrophysical spectrographs in the near-infrared, where only very few calibration sources are currently available. The compilation of a spectral line list and the characterization of line intensities and line density belong to the initial steps when investigating the feasibility of potential wavelength calibration sources. Although the molecular nitrogen spectrum was extensively studied in the past, to our knowledge, no line list exists that covers a continuous range of several thousand wavenumbers in the near-infrared. We recorded three high-resolution spectra of a nitrogen gas discharge operated at different microwave powers. The nitrogen gas is kept inside a sealed glass cell at a pressure of 2mbar. The emission lines in the spectra were fitted by a superposition of Gaussian profiles to determine their position, relative intensity, and width. The line parameters were corrected for an absolute wavelength scale, instrumental line broadening, and intensity modulation. Molecular and atomic transitions of nitrogen were identified with available line positions from the literature. We report line lists with more than 40000 emission lines in the spectral range 4500-11000cm-1 (0.9-2.2µm). The spectra exhibit emission lines over the complete spectral range under investigation with about 350-1300 lines per 100cm-1. Depending on the microwave power, a fraction of 35%-55% of all lines are blended. The total dynamic range of the detected lines covers about four orders of magnitude. Line density and peak intensities qualify the recorded discharge as a useful wavelength calibrator, and the line list provides an empirical reference for nitrogen spectra in the near-infrared. Description: The three FITS files (data_025.fit, data_050.fit and data_100.fit) contain the spectra of the nitrogen discharge operated at a microwave power of 25W, 50W, and 100W, respectively. The data format is a 1D image of the flux values. The linear wavenumber scale can be constructed from the XSTART and XEND values in the header. The line lists (tab3_025.dat, tab3_050.dat and tab3_100.dat) contain properties of the emission lines as determined from a simultaneous fit with a superposition of Gaussian profiles. See Table 3 of the associated paper for a more detailed column description. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file tab3_025.dat 173 40408 Line list for discharge operated at 25W tab3_050.dat 173 51776 Line list for discharge operated at 50W tab3_100.dat 173 58274 Line list for discharge operated at 100W list.dat 133 3 List of fits spectra fits/* 0 3 Individual fits files
Byte-by-byte Description of file (# headlines): tab3_025.dat tab3_050.dat tab3_100.dat
Bytes Format Units Label Explanations
1- 11 A11 --- Name Designation of atom or molecule 13- 24 F12.6 cm-1 nu0c Line center, calibrated 26- 37 F12.6 cm-1 nu0 Line center 39- 53 F15.6 cm-1 e_nu0 Error on line center 55- 64 F10.6 --- Ic Line intensity, flat-field corrected 66- 75 F10.6 --- I Line intensity 77- 86 F10.6 --- e_I Error on line intensity 88- 97 F10.6 cm-1 sigma Width of Gaussian line profile 99-109 F11.6 cm-1 e_sigma Error on width of Gaussian line profile 111-120 F10.6 cm-1 FWHMc Full width at half maximum of line, corrected 122-131 F10.6 cm-1 FWHM Full width at half maximum of line 133-144 F12.6 cm-1 e_FWHM Error on full width at half maximum 146-155 F10.6 cm-1 Dist Distance of line center to reference line 157-161 A5 --- flags Indicates problems encountered during analysis (1) 163-173 A11 --- Trans Transition as identified from literature
Note (1): Flags as follows: x = fit has failed or a fit parameter is at boundary condition. y = fit residuals exceed at least 11 times (=intensity threshold+noise value) the noise level and are larger than 5% of the peak intensity. b = the neighboring line is closer than the sum of their FWHM and has more than half of the line's peak intensity I (blend). r = FWHM is narrower than the resolution set for the FTS. f = σ(FWHM) is more than five time larger than the average error on FWHM (for unidentified lines) or FWHMc scatters more than five times from a linear trend for its species (for identified lines).
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 17 F17.12 cm-1 Xstar X value of the first data point 19- 34 F16.10 cm-1 Ystar X value of the last data point 36- 42 I7 --- Nx Number of data points 44- 47 I4 Kibyte Size Size of the file 49- 60 A12 --- FileName Name of the fits file in subdirectory fits 62-133 A72 --- Title Title of the file
Acknowledgements: Andreas Boesch, aboesch(at)astro.physik.uni-goettingen.de
(End) Andreas Boesch [Univ. Goettingen], Patricia Vannier [CDS] 23-Jul-2015
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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