Cassini RPWS Jupiter Encounter Calibrated Dataset

Friday 15 March 2019, by Baptiste Cecconi

This dataset contains calibrated Cassini-RPWS-HFR Jupiter fly-by data from 6 months of 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.

Access and Content

The data set is available for download at:

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

Dataset Files Description

Calibrated Flux (Binary): Jup_2000_1.flux

Binary data, 137.3 MB, little endian.

Cassini/RPWS/HFR data from 6 months of Jupiter encounter:
2000-275 (Oct 1st) 00:00 to 2001-090 (Mar 31st) 24:00

It consists of calibrated fluxes with average galactic background
substracted, then normalized 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.

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 (IDL Saveset): Jup_2000_1.sav

IDL Saveset, 4.6 MB

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:

IDL Script

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

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


IDL loading script:

IDL script

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 (IDL Saveset): jupeph.sav

IDL Saveset, 5.6 MB

IDL save set containing annex Cassini’s ephemeris data (Jovigraphic

  • 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 (Python3): cassini-jupiter-encounter.ipynb

Jupyter Notebook

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 file (full dataset): co_rpws_hfr_jupiter_cal_flux_20001001_20010331_v10.cdf

CDF, 144 MB

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