CLV of SS3

Atlas of the Third Solar Spectrum (SS3) and its Center to Limb Variation (CLV)

When using these data, please refer to the material as follows:

“The data for this analysis have been provided in electronic form by IRSOL as a compilation by Setzer et al. (2017)”

  •  M. Setzer, R. Ramelli, M. Engelhard, M.Bianda, F. Paglia, J.O. Stenflo, G. Küveler, R. Plewe, 2017,

The atlas of the Third Solar Spectrum (SS3) represents the ratio between the intensity spectrum at different distances from the solar limb and the intensity spectrum at disk center (µ = 1.0), both in units of the intensity of the local continuum level.  The observed positions of the measurements cover 9 different µ values along the solar axis ranging from 0.1 to 0.9 in step of 0.1, where  µ=cosθ is the cosine  of the heliocentric angle θ. The current version of the atlas covers the range 4384- 6610 Å and can be viewed in a pdf file showing a 10 Å wavelength section per plot page. Each page pair of the atlas contains a comparison of the intensity spectrum and the ratio for the 9 different µ-postions. The data-set is also provided as ASCII table and in IDL format.

Sometimes there are missing values (NaN)  in the intervals, where they didn’t pass the quality check. In future it is foreseen to complete the data with the missing intervals and extend the wavelength range.

At present the data are shortly described in the following proceedings paper:

R. Ramelli, M. Setzer, M. Engelhard, M. Bianda, F. Paglia, J. O. Stenflo, G. Küveler, R. Plewe, “Atlas of the solar intensity spectrum and its center to limb variation”,  Proceedings of the Solar Polarization Workshop 8, held in Florence (I), September, 12-16 2017, ASP-Conference Series arXiv:1708.03284 [astro-ph.SR].

A more detailed paper that describes these data is foreseen.


The plots are provided in the following pdf-file:

plotclv-ss3-v1.pdf (36 MBytes)

The first plot represe the spectrum at the center of the solar disk, recorded at IRSOL. The next 9 plots represent the 3rd solar spectrum for µ=0.1, µ=0.2, µ=0.3, …, µ=0.9


The data are made available in the following IDL-save file:

clv-ss3-v1.sav (20.4 MBytes)

Following array are present in the file:

WL: Wavelength (double), 4384-6610 Å
IC: I/Ic at disc center (float)
RMU01: limb / disk-center ratio at µ=0.1 (float)
RMU02: limb / disk-center ratio at µ=0.2 (float)
RMU09: limb / disk-center ratio at µ=0.9 (float)

As alternative data are provided also as a gzip-compressed ASCII table

clv-ss3-v1.txt.gz (9.1 MBytes)