FTS atlases of Stokes V

FTS atlases of the Stokes V spectra due to the longitudinal Zeeman effect

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 Stenflo (2014)”

  • Stenflo, J.O. 2014, in R. Ramelli (ed.), http://www.irsol.usi.ch/data_archive/ftsv

The recordings were made with the Kitt Peak FTS polarimeter in 1979 in various magnetic regions near disk center and reported in Stenflo et al. (A&A 131, 333-346, 1984), which is the paper that should be referred to when using these data. With the FTS all wavelengths within the range of the prefilter used are recorded simultaneously. The spectrum is fully resolved (no significant spectral smearing at all), and there is no spectral stray light. The typical band width of the prefilters used was 1000 Å. Near the edges of the band pass the spectrum gets noisy due to lack of photons, but apart from this the spectra are amazingly noise-free and clean. The spatial averaging was over a circular area 10 arcsec in diameter.

The representation is in the form of V/Ic, Stokes V in units of the continuum intensity level (and not in the form of fractional polarization V/I).

There are five separate recordings, each covering simultaneously approximately 1000 Å, represented by the following pdf files, where the ones with name FTSatlas have no smoothing, while for the ones with name FTS_vw_atlas a mild form of wavelet smoothing has been applied:

Data Files

File Contents

np: dimension (longword)
w: wavelength (Å)
b : I/Ic
v : Stokes V/Ic (unsmoothed, recommended)
vi: V/I ( = v/b, fractional polarization, unsmoothed)
vw: V/Ic with wavelet smoothing

Note that since the amplitudes of the narrow V peaks get somewhat reduced by the smoothing, it is recommended to use the v rather than the vw array in the case of precise quantitative analysis of peak amplitudes.