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

Cassini RPWS Jupiter Encounter Calibrated Dataset v1.0

Friday 22 September 2023, 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/v1.0

An archive bundle is also available for download: http://maser.obspm.fr/data/cassini/rpws/jupiter-calibrated/Cassini-Jupiter-encounter-v1.0.tgz

Other access methods:

  • Searchable Virtual Observatory Catalog accessible through VESPA. Service name: cassini_jupiter
  • das2stream service accessible on voparis-das-maser server, data service name: Cassini-RPWS-HFR/jupiter-calibrated/flux


The data consists of calibrated fluxes with average galactic background subtracted, then normalised to a distance of 1 AU from Jupiter. All different modes of acquisition have been taken into account in the calibration. Calibrated data have then been interpolated on a regular grid of 206 frequencies (48 log between 3.5 and 320 kHz, 158 lin between 375 and 16075 kHz with df=100 kHz) x 90 sec regular time steps. Levels are in log(Wm-2Hz-1), in the range -26. to -15. (i.e. zero values have been set to 1e-26 Wm-2Hz-1, and maximum values are limited to 1e-15 Wm-2Hz-1). Data gaps have been filled with constant values of -27, on the same regular time x frequency grid as above.

Coverage and sampling

  • Time range: 2000-275 (Oct 1st) 00:00 to 2001-090 (Mar 31st) 24:00
  • Time resolution: 90 seconds.
  • Spectral range: 3.5 kHz to 16.1 MHz


Calibrated Flux
Name Jup_2000_1.flux
Format Binary, little-endian
Size 137.3 MB
Description The file is a stream of binary values. It consists of 174720 consecutive spectra of 206 float (real*4) values each (integrated over 90 sec, i.e., 960 spectra/day x 182 days).
Annex Data
Name Jup_2000_1.sav
Format IDL saveset
Size 4.6 MB
Description IDL save set containing annex data.
  • AJ LONG = Array[182], format = yyyyddd
  • F FLOAT = Array[206], in kHz
  • M STRING = Array[174720], (M)onopole, (D)ipole, (1)=hybrid mode M/D
  • R DOUBLE = Array[174720], in Rj
  • T DOUBLE = Array[174720], in DOY2000.0, from 275.0 to 457.0
IDL Plotting script
Name plot_jup.pro
Format IDL script
Size 7.4 kB
Description Multi-purpose IDL plotting tool for Jup_2000_1.flux data.

Syntax: PLOT_JUP,jd,jf,step

reads and plots Jup_2000_1.flux binary file from jd to jf (DOY or DOY 2000) with step in day (integer, >=1). All parameters are optional.

Program options: [return], back, doy#, step, log, ct, ps, s, end:

  • [return] = next screen
  • back = previous screen
  • doy# = enter doy number to go directly to that day
  • step = change step (in days)
  • log = toggles log/linear frequency scale
  • ct = change color table
  • ps = postscript plot of present screen
  • s = plot spectrum after time interval selection with cursor
  • end = exit program

    Calls read_jup.pro, spdynps.pro, dyn.pro

IDL loading script
Name read_jup.pro
Format IDL script
Size 2.1 kB
Description Allows to read a selected portion of the binary file Jup_2000_1.flux
and corresponding annex data from Jup_2000_1.sav

Syntax: READ_JUP, jd,hd,jf,hf,dsec,fmin,fmax,x,f,t,r,m,d,u,/noprint,/noant


  • jd,hd = day,hour begin with jd in DOY or DOY 2000 and hr in hour
  • jf,hf = day,hour end
  • fmin,fmax = spectral range in kHz
  • dsec = time integration in seconds, by multiple of 90s (if des: c<90 -> dsec=dsec x 90 sec)

    Output data are

  • x = data in log(Wm-2Hz-1)
  • t in decimal DOY 2000
  • f in kHz
  • r in Rj
  • m,d,u = fraction of spectra of type ’M’, ’D’, ’1’ per interval dsec (0 to 1 each)

    A help for the command line is included in HELP_READ_JUP

    read_jup deals automatically with little/big endian swap depending on the platform used.

Ephemeris data
Name jupeph.sav
Format IDL Saveset
Size 5.6 MB
Description IDL save set containing annex Cassini’s ephemeris data (Jovigraphic coordinates).
  • IOPH FLOAT = Array[174720] Io phase (deg)
  • LAT FLOAT = Array[174720] Latitude (deg)
  • LON FLOAT = Array[174720] West Longitude (deg)
  • MLAT FLOAT = Array[174720] Magnetic Latitude (deg)
  • RE FLOAT = Array[174720] R (Rj) 1 Rj = 71492.0 km
  • TE DOUBLE = Array[174720] DOY2000.0, from 275.0 to 457.0
  • TL FLOAT = Array[174720] Local Time (hrs)

    IOPH and LON are increasing with time, use mod 360 for a value between 0 and 360 deg. TE, RE are identical to T,R in Jup_2000_1.sav.

Jupyter Notebook
Name cassini-jupiter-encounter.ipynb
Format Jupyter Notebook (python3)
Size 336 kB
Description Jupyter Notebook showing an example of how to load and display the
dataset. The code to produce the CDF file is also provided.
  • Requires: Python 3.5
  • Dependencies: spacecy, scipy, numpy, matplotplib
CDF data (full dataset)
Name co_rpws_hfr_jupiter_cal_flux_20001001_20010331_v10.cdf
Format CDF
Size 144 MB
Description CDF (Common data format) file compiling data from the 3 data files of this dataset: Jup_2000_1.flux, JUP_2000_1.sav, jupeph.sav.

List of variables:

  • EPOCH CDF_TIME_TT2000 174720
  • FLUX CDF_REAL4 174720 x 206
  • IO_PHASE CDF_REAL4 174720
  • MODE CDF_CHAR 174720

    This file is compliant with CDF-ISTP (International Solar-Terrestrial Program and CDF-PDS4 (NASA Planetary Data System version 4) format recommendations.


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


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


  • 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

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