Observatoire de Paris-PSL CNRS vopdc cdpp Sorbonne Université cnes Université de Paris LESIA

Analysis of Saturn kilometric radiation polarization throughout the Cassini mission: Supplementary material

Wednesday 16 September 2026, by Baptiste Cecconi

This dataset provides the the Data and Software required for the processing of SKR polarization done by Fischer et al. in the paper "Analysis of Saturn kilometric radiation polarization throughout the Cassini mission".

Link to data repository

Description

Data directory
This directory gives one simple text file of Cassini ephemeris data in the Saturn geographic coordinate system from 2004 until 2017 for each hour at minute 30 (CassiniAtSat_geo_halfhour_2004_2017.dat).
The other files are csv-files (to be read with Excel or a simple text editor like Notepad++) for each quarter of year (001-090, 091-180, 181-270, 371-366) from 2004 until 2017. Each file contains hourly calculated SKR polarization parameters from 100-1200 kHz. The data file columns are described in the table below.

The data file column description
Column nameDescriptionUnit
index index of row within the file
Year year yr
DOY day of year d
HH hour hr
num number of data points within hour
 num_lp number of data points with linear polarization >0.2
cpf circular polarization fraction (number of datapoints with linear polarization <0.2 divided by total number of data points)
lpf linear polarization fraction
mlin mean linear polarization degree
mdlin median linear polarization degree
dlin standard deviation of linear polarization degree
mcirc mean circular polarization degree
mdcirc median circular polarization degree
dcirc standard deviation of circular polarization degree
mtot mean total polarization degree
mdtot median total polarization degree
dtot standard deviation of total polarization degree
ms mean flux V^2/m^2/Hz
mds median flux V^2/m^2/Hz
 ds standard deviation of SKR flux V^2/m^2/Hz

Software/ directory
The software for data processing was written in Python (*.py) and Matlab(*.mat) by Dorian Jost and Georg Fischer, respectively. Some software files cannot simply be run, because they need various data files in specific directories, which are not provided here. We have the following programs:

  • readfile.py: for reading binary Meudon data files of the RPWS High Frequency Receiver (HFR)
  • readn2.m: read Meudon n2 data of RPWS/HFR
  • readn3b.m: read Meudon n3b data of RPWS/HFR
  • readn3d.m: read Meudon n3d data of RPWS/HFR
  • spectrograms.py: this program imports n2 and n3d data to make daily spectrograms of flux and polarization
  • Plotn3dday.m: this program also imports n2 and n3d data to make daily spectrograms of flux and polarization. It uses Cassini ephemeris and attitude data to display the position of Cassini in distance, latitude and local time and it also displays the so-called beta-angles which give the angles between the center of Saturn and various antenna planes. All these Cassini ephemeris and attitude data is not provided here. Program was used for Figure 1.
  • Plotn3bhour.m: this program imports n2 and n3b data to make spectrograms of flux and polarization over two hours. Similar to before, it needs various data (n3b, ephemeris, attitude). It was used for Figure 8.
  • CohenSKR.m: simple m-file to calculate the values of Table 1 using equations of Cohen (1960).
    skrpolarization.py: Python program to calculate hourly averaged SKR polarization properties according to the conditions mentioned in Section 2.3. It produces all the csv.files provided in the Data directory.
  • SKRlct.m: m-file which uses csv-files to produce plots SKR polarization as function of time (Figure 2).
  • SKRpol.m: m-file using csv-files to produce plots of paper (Figures 3 and 7).
  • SKRpol2.m: m-file using csv-files to produce plots of paper (Figures 4 and 5).
  • SKRpol7.m: m-file using csv-files to produce Figure 6 of paper.
  • SKRpolexp.m: m-file producing schematic diagram of model/explanation for SKR polarization (Figure 9).

Additional comment
The following 5 time intervals also had to be excluded for the calculation of the SKR polarization due to bad Meudon n3d data (wrong calculation for the center of Saturn seen from the spacecraft): For the year 2008 all days with DOY>=272, for the year 2009 all days in the interval 003<=DOY<072, for the year 2014 from 091<=DOY<111, for the year 2015 from 181<=DOY<235, and for the year 2017 it was the interval 003<=DOY<050.

Coverage

  • Time interval: 2004/01/01 - 2017/09/15
  • Spectral range: 100-1200 kHz

Acknowledgments
G. F. and D. J. acknowledge full support from the Austrian Science Fund FWF in the frame of the Austrian–Czech project ”Open questions about Saturn’s radio emissions” (doi:10.55776/I6710).

References

  • Cohen, M. H. (1960). Magnetoionic Mode Coupling at High Frequencies. Astrophys. J., 131 , 664. doi:10.1086/146878.
  • Fischer, G., Cecconi, B., Lamy, L., Ye, S. Y., Taubenschuss, U., Macher, W., Zarka, P., Kurth, W. S., and Gurnett, D. A. (2009). Elliptical polarization of Saturn Kilometric Radiation observed from high latitudes. Journal of Geophysical Research (Space Physics), 114 (A8), A08216. doi:10.1029/2009JA014176

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