{
  "HAPI": "3.1",
  "status": {
    "code": 1200,
    "message": "OK"
  },
  "startDate": "1996-05-25T00:00:00.000Z",
  "stopDate": "2002-11-06T00:00:00.000Z",
  "parameters": [
    {
      "name": "SCET",
      "length": 24,
      "description": "Spacecraft Event Time (SCET) corresponding to the density measurement. As described in the METHOD field below, data on this volume were gather via three different proceedures. For data collected from individual spectrum line plots the SCET value is the start time of the corresponding PWS frequency sweep, (METHOD='line'). For data gathered from spectrogram plots, either manually (METHOD='spec') or via an algorithm (METHOD='auto'), this time is merely the X axis position selected for a measurement and thus does not correspond to the start time of any particular PWS frequency sweep. The format of this ASCII text field is: yyyy-mm-ddThh:MM:ss.SSS where yyyy is the 4-digit year, mm is the 2-digit month number (january = 1), dd is the 2-digit day of month, hh is the hour of the day on a 24-hour clock, MM is the minute of the hour, ss is the second of the minute and SSS is 3-digit millisecond of the second.",
      "units": "UTC",
      "type": "isotime",
      "fill": null
    },
    {
      "name": "RADIUS",
      "description": "The distance from the center of Jupiter to the spacecraft (in kilometers) divided by the radius of Jupiter at the equator (71492 km).",
      "units": "Jupiter Radii",
      "type": "double",
      "fill": null
    },
    {
      "name": "LONGITUDE",
      "description": "Jovian system III west longitude in degrees. Valid range is 0 to 360.",
      "units": "deg",
      "type": "double",
      "fill": null
    },
    {
      "name": "LOCAL_TIME",
      "description": "Provides the rotation angle between two planes containing Jupiter's rotation axis. The first plane is formed by the spin axis and the center of the Sun. The second plane is formed by rotating the first plane about the spin axis until it contains the instananeous location of the Galileo spacecraft. The value is expressed as decimal hours instead of degrees and offset by 12 hours. Thus 0 degrees maps to 12.0 hours (noon), 90 degrees to 18.0 hours (dusk), 180 degrees to 0.0 hours (midnight), and 270 degrees to 6.0 hours (dawn).",
      "units": "Hours",
      "type": "double",
      "fill": null
    },
    {
      "name": "LATITUDE",
      "description": "Jovian latitude in degrees, valid range is -90 to +90.",
      "units": "deg",
      "type": "double",
      "fill": null
    },
    {
      "name": "MAGNETIC_LOCAL_TIME",
      "description": "Provides the rotation angle between two planes containing the Jovian magnetic dipole axis. The first plane is formed by the dipole axis and the center of the Sun. The second plane is formed by rotating the first plane about the dipole axis until it contains the instananeous location of the Galileo spacecraft. The value is expressed as decimal hours instead of degrees and offset by 12 hours. Thus 0 degrees maps to 12.0 hours (noon), 90 degrees to 18.0 hours (dusk), 180 degrees to 0.0 hours (midnight), and 270 degrees to 6.0 hours (dawn).",
      "units": "deg",
      "type": "double",
      "fill": null
    },
    {
      "name": "MAGNETIC_LATITUDE",
      "description": "The angle between Jovian magnetic equatorial plane and the line from the center of the diopole to the Galileo spacraft's instantaneous position.",
      "units": "deg",
      "type": "double",
      "fill": null
    },
    {
      "name": "JSE_X",
      "description": "The Jovicentric Solar Ecliptic (JSE) X axis is chosen to point from Jupiter's equator towards the Sun. The units are measured in Jovian radii where 1 Jovian radii is equal to 71492 km.",
      "units": "Jupiter Radii",
      "type": "double",
      "fill": null
    },
    {
      "name": "JSE_Y",
      "description": "The JSE Y axis is chosen to be in the ecliptic plane and points toward Jupiter's dusk (thus opposing planetary motion). The units are measured in Jovian radii where 1 Jovian radii is equal to 71492 km.",
      "units": "Jupiter Radii",
      "type": "double",
      "fill": null
    },
    {
      "name": "JSE_Z",
      "description": "The JSE Z axis is chosen to be parallel to the ecliptic pole. This axis is defined as the cross product of Jupiter's velocity vector j and the x-axis. The units are measured in Jovian radii where 1 Jovian radii is equal to 71492 km.",
      "units": "Jupiter Radii",
      "type": "double",
      "fill": null
    },
    {
      "name": "FREQ_CE",
      "description": "Electron cyclotron frequency measured in Hz. This term can be approximated by multiplying 28 times the magnetic field strength in nT, which is measured by the magnetometer insturment. If magnetometer data is absent, this field is empty. If there are no magnetic field data then the electron cyclotron frequency cannot be determined. Therefore, during periods when this value is absent, the density can only determined if the measured frequency is the plasma frequency cutoff (see field MEASURED_FREQ_ABBREV).",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "METHOD",
      "length": 4,
      "description": "Data on this volume were collected using three different tool sets. When using the first set, the technician selected a single single point on an amplitude-frequency line plot. When using the second tool set, points were digitized from a color spectrogram of amplitude versus frequency and time. For the third method, a technician placed boundaries were around cutoffs or peaks and an algorithm auto-selected the steepest amplitude drop (cutoff) or the peak value. Possible values for this field and thier meanings and data cadance implications are given below: 'line' - Amplitude vs. Frequency. One density measurement per PWS spectrum. Time values in the SCET field match upstream PWS dataset to milliseconds. 'spec' - Amplitude vs. Frequency and Time Density measurement cadenace depends on human operator. Data points are roughly 30 seconds to 90 seconods apart. Time values of the SCET field do not match upstream PWS spectra times. 'auto' - Values were auto-selected from Amplitue vs. Frequency data via an algorithm. The algorithm operated within time and frequency boundaries selected by a technician. Data points are exactly 60 seconds apart and occur on the half-minute mark. Time values of the SCET field do not match upstream PWS spectra. No matter the method used to collect the initial frequency measurement all values were verified by a human technician using plots of PWS spectrograms with a measured-frequency overlay.",
      "units": null,
      "type": "string",
      "fill": null
    },
    {
      "name": "MEASURED_VALUE",
      "description": "This value is the frequency in Hz, measured from Galileo PWS SURVEY spectra, that is used to calculate the electron number density as well as the remaining frequencies of interest. This frequency will be identical to one of the four characteristic frequencies shown in subsequent fields.",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "QUALITY_INDEX",
      "description": "An integer between 0 and 3 which gives a qualitative description for the accuracy of a frequency measurement. For measurement made from cutoff characteristic frequencies a data quality index of 0 is given when a sharp cutoff is present within a spectrum containing minimal background noise. Conversely, a quality index of 3 is given for measurements taken from a very noisy background spectrum and where the cutoff is not well- defined.",
      "units": null,
      "type": "integer",
      "fill": null
    },
    {
      "name": "MEASURED_ITEM",
      "length": 1,
      "description": "A letter is given to label which characteristic frequency of the plasma was used to calculate the density. Any of the four characteristic frequencies shown below can be measured and used with the cyclotron frequency to determine the density. The table below displays the characteristic frequencies used to calculate the density along with their corresponding common notation and abbreviated value. +----------------------------------------------------------------+ | Frequency | Common | Measured_Freq_Abbrev | | Name | Notation | Value | +----------------------------------------------------------------+ | Electron Plasma Frequency | fpe | p | | | | | | R=0 Frequency | fR=0 | R | | | | | | L=0 Frequency | fL=0 | L | | | | | | Upper Hybrid Frequency | fUH | u | +----------------------------------------------------------------+",
      "units": null,
      "type": "string",
      "fill": null
    },
    {
      "name": "SOLAR_WIND",
      "description": "This column is 0 if Galileo was determined to be within Jupiter's magnetopause at the time of the density determination, 1 if the location was outside the magnetopause, in the solar wind. Most of the time, this would indicate a location in the magnetosheath, or shocked solar wind, but could be upstream of the bow shock, as well.",
      "units": null,
      "type": "integer",
      "fill": null
    },
    {
      "name": "FREQ_PE",
      "description": "The electron plasma frequency in Hz as either measured directly from the Galileo PWS SURVEY data or calculated from the equations of cold plasma theory using the MEASURED_FREQUENCY measurement and the cyclotron frequency.",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "FREQ_L0",
      "description": "The L=0 frequency in Hz as either measured directly from the Galileo PWS SURVEY data or calculated from the equations of cold plasma theory using the MEASURED_FREQUENCY measurement and the cyclotron frequency. If magnetometer data is absent, this field is empty.",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "FREQ_R0",
      "description": "The R=0 frequency in Hz as either measured directly from the Galileo PWS SURVEY data or calculated from the equations of cold plasma theory using the MEASURED_FREQUENCY measurement and the cyclotron frequency. If magnetometer data is absent, this field is empty.",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "FREQ_UHR",
      "description": "The upper hybrid frequency in Hz as either measured directly from the Galileo PWS SURVEY data or calculated from the equations of cold plasma theory using the MEASURED_FREQUENCY measurement and the cyclotron frequency. If magnetometer data is absent, this field is empty.",
      "units": "Hz",
      "type": "double",
      "fill": null
    },
    {
      "name": "ELECTRON_DENSITY",
      "description": "Electron number density in cm**-3 as determined from frequency measurements of the plasma (shown in the MEASURED_FREQ column) and equations of cold plasma theory. If the MEASURED_FREQ field does not read 'p' and MAG data are not available this field is empty",
      "units": "cm**-3",
      "type": "double",
      "fill": null
    }
  ],
  "x_LastUpdate": "2026-05-12T15:18:52Z"
}