# Three high resolution solar atlases of the 3000 Å - 9900 Å range

Jean-Marie Malherbe

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Jean-Marie Malherbe. Three high resolution solar atlases of the 3000 Å - 9900 Å range. observatoire paris. 2025. hal-04972769

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Submitted on 1 Mar 2025

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# Three high resolution solar atlases of the [3000 Å - 9900 Å] range

*Jean-Marie Malherbe (emeritus astronomer)*

Observatoire de Paris, PSL Research University, LIRA, France

Email: [Jean-Marie.Malherbe@obspm.fr](mailto:Jean-Marie.Malherbe@obspm.fr); ORCID: [https://orcid.org/0000-0002-4180-3729](https://orcid.org/0000-0002-4180-3729)

25 February 2025

## ABSTRACT

We present a set of useful high resolution atlases of the Sun in FITS format, originally produced by Delbouille et al (1972), Kurucz et al (1972) at disk centre, and Gandorfer (2000, 2002, 2005) close to the limb ($\mu = \cos\theta = 0.1$). The ZIP file contains the FITS data (wavelength and intensity) together with derived sets of PNG spectral images of 100 Å bandwidth.

## KEYWORDS

Sun, disk centre, visible spectrum, high resolution, atlas

## THE SETS OF DATA (FILE ATLASES.ZIP)

Delbouille's atlas from 3000 Å to 9900 Å has a spectral resolution of 0.002 Å. It was obtained at the Jungfraujoch station (3500 m, Switzerland) so that atmospheric lines (such as H₂O) are often faint in comparison to ground based observations. The FITS files contain the wavelength in mÅ (long integers) while intensities (short integers) are normalized to 10000 (the continuum). A curve of theoretical circular polarization rates ($V/I = 4.67 \times 10^{-13} \text{ g } \lambda^2 \text{ B dLn(I)/d}\lambda$) is incrusted in PNG spectral images for B = 1000 G and g = 1) to give a rough idea of the Zeeman line sensitivity to the magnetic field B. The unit is the percent (100 V/I is plotted). The V/I = 0 line is indicated together with 10% increments (dotted lines from -40% to +40% V/I polarization). We used the Moore table for line identification (the ASCII file Moore.txt) and equivalent Lande factors are reported when available (the ASCII file Lande.txt).

Kurucz's atlas from 3000 Å to 9900 Å has a spectral resolution of 0.005 Å. It was obtained at the National Solar Observatory (USA). The FITS files contain the wavelength in mÅ (long integers) while intensities (short integers) are normalized to 10000 (the continuum). In the associated PNG spectral images, we used the Moore table for line identification (the ASCII file Moore.txt) and equivalent Lande factors are given when known (the ASCII file Lande.txt). See also for atlases http://kurucz.harvard.edu/sun.html and http://kurucz.harvard.edu/linelists.html for laboratory line lists.

Gandorfer's atlas from 3160 Å to 6990 Å has a spectral resolution of 0.005 Å. It was obtained at IRSOL Locarno (Switzerland). The FITS files contain the wavelength in mÅ (long integers) and intensities close to the limb ($\mu = \cos\theta = 0.1$); the values (short integers) are normalized to 10000 (the continuum). In the associated spectral PNG images, a curve of linear polarization rates ($Q/I > 0$ in %) is incrusted, this is called the second solar spectrum (it is very small, a fraction of 1%, except for a few lines in the blue); there is a 0.25% increment in Q/I between each dotted line. The dashed line is the continuum polarization level. In the FITS file, the polarization rate $Q/I$ is multiplied by $10^5$ (short integers) or 1000 if expressed in percent. We used the Moore table for line identification (the ASCII file Moore.txt) and equivalent Lande factors are indicated when known (the ASCII file Lande.txt). See also the second solar spectrum archive at https://www.irsol.usi.ch/it/data_archive/ss2
# REFERENCES

If you use these solar spectra, please acknowledge :

* Delbouille L., Neven L., Roland G., 1972, PHOTOMETRIC ATLAS OF THE SOLAR SPECTRUM FROM λ 3000 TO λ 10000

* Gandorfer, A. 2000, The Second Solar Spectrum: A high spectral resolution polarimetric survey of scattering polarization at the solar limb in graphical representation. Volume I: 4625 Å to 6995 Å. Zurich: VdF

* Gandorfer, A. 2002, The Second Solar Spectrum: A high spectral resolution polarimetric survey of scattering polarization at the solar limb in graphical representation. Volume II: 3910 Å to 4630 Å. Zurich: VdF

* Gandorfer, A. 2005, The Second Solar Spectrum: A high spectral resolution polarimetric survey of scattering polarization at the solar limb in graphical representation. Volume III: 3160 Å to 3915 Å. Zurich: VdF

* Kurucz, R., Furenlid, I., Brault, J., Testerman, L., 1984, Solar flux atlas from 296 to 1300 nm, rerReduced by Kurucz, R., 2005 for 300 to 1000 nm