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J/A+A/507/417       Oxygen lines in solar granulation. I.    (Pereira+, 2009)

Oxygen lines in solar granulation. I. Testing 3D models against new observations with high spatial and spectral resolution. Pereira T.M.D., Kiselman D., Asplund, M. <Astron. Astrophys. 507, 417 (2009)> =2009A&A...507..417P
ADC_Keywords: Sun ; Spectroscopy Keywords: Sun: granulation - line: formation - Sun: photosphere techniques: spectroscopic - techniques: high angular resolution Abstract: We seek to provide additional tests of the line formation of theoretical 3D solar photosphere models. In particular, we set out to test the spatially-resolved line formation at several viewing angles, from the solar disk-centre to the limb and focusing on atomic oxygen lines. The purpose of these tests is to provide additional information on whether the 3D model is suitable to derive the solar oxygen abundance. We also aim to empirically constrain the NLTE recipes for neutral hydrogen collisions, using the spatially-resolved observations of the OI 777nm lines. Description: We obtained solar observations of several lines at several positions of the solar disk. Data were obtained in May 2007 with the TRIPPEL spectrograph at the Swedish 1-m Solar Telescope (SST). The spectra were obtained for three distinct wavelength windows at approx 615, 630 and 777nm. Each window covers ∼1nm. The spectra are spatially-resolved in the solar surface, hence are given as 2D spectrograms. One axis covers the wavelength and the other spatial position. The observations are given for five positions in the solar disk, ordered by mu, the cosine of the heliocentric angle. The objective was to study the centre-to-limb variation of the lines. Active sun regions were avoided. In total 150 spectrograms are given for each wavelength window: 50 for the solar disk-centre (mu=1) and 25 for the other four positions (mu=0.8, 0.6, 0.4, 0.2). The images were selected by continuum contrast, hence their observed times are not the same for the three windows. The spectrograms are given as FITS files. Each file has two Header/Data Units (HDU). The first HDU contains the reduced spectrogram, a 2D array. The first dimension of the array contains (FITS NAXIS1) corresponds to wavelength, and the second (FITS NAXIS2) to spatial coordinate. The second HDU contains the continuum levels obtained for each spatial point (1D array, length equal to the number of spatial points in the spectrogram). To obtain the normalized reduced spectrogram one has to divide each spectrum in the spectrogram by the corresponding continuum level. The spectrograms have been corrected for stray light and to minimize noise a Fourier filter has been applied (details in the paper). Important note: the wavelength scales have NOT been corrected for solar rotation or gravitational redshift. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 99 450 Observations wave/* 9 15 Wavelength scale for the spectrograms, lambda=6150, 6300 and 7770Å, mu=0.2, 0.4, 0.6, 0.8 and 1 sp/* 0 15 Directories by wavelength (spAAAAA) with individual spectra in FITS format
See also: J/A+A/508/1403 : Oxygen lines in solar granulation. II. (Pereira+, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 nm lambda Approximate central wavelength of filter 6- 20 F15.7 d JD Julian date 23- 28 F6.2 deg HLAT Heliographic latitude in the Stony-Hurst coordinate system 31- 36 F6.2 deg HLON Heliographic longitude in the Stony-Hurst coordinate system 39- 43 F5.3 --- mu Cosine of the heliocentric angle 46- 50 F5.3 --- e_mu Error in mu 53- 56 F4.2 --- S Amount of straylight removed from the the spectra. Expressed as a percentage of the pseudo-continuum intensity 59- 64 F6.4 arcsec/pix Conv Approximate conversion factor from the spectrogram's spatial axis to angular coordinate in arcsec 67- 86 A20 --- FITSfile Path and filename of each spectrogram, in subdirectory "sp" 88- 99 A12 --- WaveFile Name of the file with wavelength scale, in subdirectory "wave"
Byte-by-byte Description of file: wave/*
Bytes Format Units Label Explanations
1- 9 F9.5 nm Lambda Wavelength scale for the corresponding spectrograms (1)
Note (1): It decreases with pixel number (ie., first pixel of the spectrogram's wavelength axis has the largest wavelength)
Acknowledgements: Tiago M. D. Pereira, tiago(at)
(End) Patricia Vannier [CDS] 24-Sep-2009
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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