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

Cassini RPWS Jupiter Encounter Calibrated Dataset v2.0

Wednesday 8 September 2021, by Baptiste Cecconi

This dataset contains calibrated radio flux density data observed by Cassini-RPWS-HFR during 6 months around its Jupiter encounter: 2000-275 (Oct 1st) 00:00 to 2001-090 (Mar 31st) 24:00. The spectral range covers 3.5 kHz to 16 MHz.

Link to data repository

The data files are available here: http://maser.obspm.fr/data/cassini/rpws/jupiter-calibrated/v2.0

An archive bundle is also available for download: http://maser.obspm.fr/data/cassini/rpws/jupiter-calibrated/Cassini-Jupiter-encounter-v2.0.tgz

Description

This dataset is an update for the previous version (version 1.0 available at https://doi.org/10.25935/H98J-MA66).

The content of this dataset complements that of the previous one, corresponding to the analysis conducted in Zarka (2004).

The flux density (Jup_2000_1.sav, available in version 1.0 dataset) and ephemeris (jupeph.sav, available in version 1.0 dataset) data were gathered, with new thresholding and gaps labelling, using the program make_jupiter_cassini_sav.pro to produce the new save-set Jupiter_Cassini.sav where flux density data is in the array x(174720, 206).
The data was recorded in 3 RPWS modes: Monopole (-79% of the time), Dipole (-5%), and Mixed (-5%). Gaps represent -11% of the time.

The program integ_jup.pro performed the detrending in 2 different ways. The original flux density data were renamed x_raw (174720 x 206) and the detrended data produced are x1 (174720 x 206) and x2 (174720 x 206).

  • As decribed in the paper Zarka (2020), table x1 results from (i) subtraction from spectra in each of the above 3 modes of a background recomputed separately for each mode, followed by (ii) interpolation of isolated spikes < -4σ- or > 10σ- on surrounding values at the same frequency.
  • As an alternative detrending,
    x2 results from (i) equalization of re-computed backgrounds to the one in Monopole mode (i.e. no background subtraction but only subtraction from each spectrum in Dipole or Mixed mode of the difference between the corresponding background and the one in Monopole mode), followed by (ii) interpolation of isolated spikes < -4σ- or > 10σ- on surrounding values at the same frequency, then (iii) subtraction of a polynomial (parabolic) fit of the residual long term variation at each frequency, (iv) equalization of intensity histograms at each frequency relative to each other, and (v) a second pass of spikes elimination (ii).
    Results are similar, except that x2 preserving better very low values down to -20 dB of the Galactic background (that are rather set to 0 dB in x1).
    Gaps are set to -1.

Circular polarization was then computed from Cassini data (kronos database in Meudon) using the program high_res_plot.pro called for each day of Jupiter_Cassini_2.sav by batch_high_res_plot.pro using the frequency ramp framp.sav from Jupiter_Cassini_2.sav
Results were gathered in a single array xpol(174720, 206).
The content of Jupiter_Cassini.sav (with x renamed x_raw) plus x1, x2 (detrended flux densities) and xpol (circular polarization) were saved in Jupiter_Cassini_3.sav

The catalog of radio components contours is in emissions.sav
The save sets emissions.sav and Jupiter_Cassini_3.sav can be used together by the program plot_all_3.pro to produce the summary plots in allplots_3.pdf

Acknowledgements

The Cassini/RPWS/HFR Jupiter Flyby Calibrated data collection has been produced by Zarka, P., B. Cecconi, F. P. Magalhães, C. K. Louis & L. Lamy from the Observatoire de Paris/LESIA Cassini-RPWS team, with the support of CNRS and CNES.

Contact

Any question or request should be addressed to contact.maser@obspm.fr

References

  • Zarka, P., B. Cecconi, and W. S. Kurth. 2004. Jupiter’s Low-Frequency Radio Spectrum From Cassini/Radio and Plasma Wave Science (RPWS) Absolute Flux Density Measurements. J. Geophys. Res. 109: A09S15. doi:10.1029/2003JA010260
  • Zarka, P. & Cecconi, B. (2019). Cassini RPWS Jupiter Encounter Calibrated Dataset (Version 1.0) [Data set]. PADC. https://doi.org/10.25935/H98J-MA66
  • Zarka, P. & F. P. Magalhães, M. S. Marques, C. K. Louis, E. Echer, L. Lamy, B. Cecconi, and R. Prangé (2021). Jupiter’s auroral radio emissions observed by Cassini: rotational versus solar wind control, and components identification. J. Geophyss Res.. accepted.