| DATA_SET_DESCRIPTION |
Data Set Overview
=================
THIS DATA SET CONTAINS ELECTRON PARAMETERS IN THE PLS ENERGY
RANGE (10-5950 EV) AT SATURN DURING THE VOYAGER 2 ENCOUNTER.
PARAMETERS ARE CALCULATED IN SEVERAL WAYS. TOTAL MOMENT
DENSITY AND TEMPERATURE ARE GIVEN. EACH ELECTRON SPECTRUM IS
ALSO FIT WITH A THERMAL COMPONENT AND 1-3 HOT COMPONENTS
DEPENDING ON HOW MANY MAXWELLIANS ARE NEEDED TO FIT THE ENTIRE
DISTRIBUTION. THE MOMENT DENSITY AND TEMPERATURE OF THE HOT
COMPONENT IS CALCULATED AFTER THE THERMAL COMPONENT IS
SUBTRACTED FROM THE SPECTRUM. THE CHI-SQUARE VALUE FOR EACH
FIT IS GIVEN. THE SPACECRAFT CHARGE IS NOT CALCULATED
CONSISTENTLY, AND MAY RESULT IN FACTOR OF 2-3 ERRORS IN THE
THERMAL ELECTRON DENSITY. DATA IS UNRELIABLE INSIDE 6 RS AND
IN THE OCCULTATION REGIONS. A COMPLETE DESCRIPTION OF THIS
DATA SET IS IN SITTLERETAL. (1983).
FITTING PARAMETERS ARE DESCRIBED AS BELOW:
===============================================================
name type description
---------------------------------------------------------------
time A24 time in the format yyyy-mm-ddThh:mm:ss.sssZ
imax I2 points in spectrum
ifly I1 flag value: 1 = encounter, 0 = cruise
thbn 1PE9.3 angle between d cup normal and mag. field
vector (radians)
rne 1PE9.3 moment electron density (cnts/cm**3)
rte 1PE9.3 moment electron temperature (eV)
phisc 1PE9.3 spacecraft potential (V)
rnc 1PE9.3 cold electron density (cnts/cm**3)
sgnc 1PE9.3 std. dev. of cold electron density (rnc)
(cnts/cm**3)
rtc 1PE9.3 cold electron temperature (eV)
sgtc 1PE9.3 std. dev. of cold electron temperature
(rtc) (eV)
chic 1PE9.3 chi squared of the cold fit
rnh1 1PE9.3 first hot electron density (cnts/cm**3)
sgnh1 1PE9.3 std. dev. of first hot electron dens.
(rnh1) (cnts/cm**3)
th1 1PE9.3 first hot electron temperature (eV)
sgth1 1PE9.3 std. dev. of first hot electron temp.
(th1) (eV)
chih1 1PE9.3 chi squared of the first hot fit
rnh2 1PE9.3 second hot electron density (cnts/cm**3)
sgnh2 1PE9.3 std. dev. of second hot electron dens.
(rnh2) (cnts/cm**3)
th2 1PE9.3 second hot electron temperature (eV)
sgth2 1PE9.3 std. dev. of second hot electron temp.
(th2) (eV)
chih2 1PE9.3 chi squared of second hot fit
rnh3 1PE9.3 third hot electron density (cnts/cm**3)
sgnh3 1PE9.3 std. dev. of third hot electron dens.
(rnh3) (cnts/cm**3)
th3 1PE9.3 third hot electron temperature (eV)
sgth3 1PE9.3 std. dev. of third hot electron temp.
(th1) (eV)
chih3 1PE9.3 chi squared of third hot fit
chi 1PE9.3 chi squared for total fit
rnh 1PE9.3 moment of the hot electron density
(cnts/cm**3)
rth 1PE9.3 moment of the hot electron temperature
(eV)
IN COMPUTING RNH1 AND TH1 WE USED THE 3RD TO 7TH CHANNELS ABOVE
THE BREAKPOINT ENERGY EB1 AND SUBTRACTED THE COLD COMPONENT FC
FROM FE (OBSERVED) BEFORE DOING THE FIT. IN REALITY THIS FIT
WAS DONE ITERATIVELY BETWEEN THE COLD AND HOT COMPONENT FITS
(FC=FE-FH AND FH=FE-FC ETC.). A SIMILAR APPROACH WAS USED IN
COMPUTING RNH3,TH3 FOR WHICH A MAXWELLIAN FIT WAS DONE TO THOSE
CHANNELS ABOVE EB2. THE PARAMETERS RNH2,TH2 WERE FIT TO THE
UPPER 5 (3 MIN) CHANNELS (GENERALLY ABOVE EB2). THIS FIT WAS
PRIMARILY DONE TO ALLOW PROPER ESTIMATION OF FE TO THE HIGH
ENERGY PORTION OF THE SPECTRUM. IN MANY CASES THERE ARE NOT
SUFFICIENT POINTS TO COMPUTE RNH3,TH3 AND RNH2,TH2 DO PROVIDE
A FAIR REPRESENTATION OF THE SPECTRUM. IF RNH1=RNH2=RNH3 THEN
YOU SHOULD NOT USE THE 2ND AND 3RD FIT PARAMETERS. VALUES OF
1.E32 INDICATE THAT THE PARAMETER COULD NOT BE OBTAINED FROM
THE DATA USING THE STANDARD ANALYSIS TECHNIQUE. ADDITIONAL
INFORMATION ABOUT THIS DATASET AND THE INSTRUMENT WHICH PRODUCED
IT CAN BE FOUND ELSEWHERE IN THIS CATALOG. AN OVERVIEW OF THE
DATA IN THIS DATA SET CAN BE FOUND IN SITTLER ET AL. (1983) AND
A COMPLETE INSTRUMENT DESCRIPTION CAN BE FOUND IN BRIDGE (1977).
Processing Level Id : 5
Software Flag : Y
Parameters
==========
Sampling Parameter Name : TIME
Data Set Parameter Name : ELECTRON DENSITY
Sampling Parameter Resolution : 96.000000
Sampling Parameter Interval : 96.000000
Minimum Available Sampling Int : 96.000000
Data Set Parameter Unit : CM-3
Sampling Parameter Unit : SECOND
Description
-----------
A derived parameter giving an indication of the mean A
derived parameter equaling the number of electrons per unit
volume over a specified range of electron energy.
energy/electron, assuming the shape of the electron energy
Different forms of electron density are derived spectrum to
be Maxwellian (i.e. highest entropy shape). Given
distinguished by method of derivation (Maxwellian fit, that
the electron energy spectrum is not exactly Maxwellian,
method of moments) or by the some selection criteria (ie.,
the electron temperature can be defined integrally (whereby
the mean energy obtained by integrating under the actual hot
electron and cold electron density). In general, if more
electron energy spectrum is set equal to the integral under
than one electron component is analyzed, either by moment or
fit, a total density will be provided which is the sum of a
Maxwellian, where the temperature is a free parameter for the
electron densities. If the electron do not have a which to
solve), or differentially (whereby the slopes of Maxwellian
distribution the actual distribution can be the actually
electron energy spectrum at various energies are matched to
the slopes of a corresponding Maxwellian). represented as
the sum of several Maxwellians, in which case the density of
each Maxwellian is given. The temperature parameter is often
qualified with a range of applicable energies. temperatures
can be angularly anisotropic. If the electrons do not have a
Maxwellian distribution the actual distribution can be
represented as the sum of several Maxwellians, each with a
separate temperature.
Source Instrument Parameters
============================
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON DENSITY
Instrument Parameter Name : ELECTRON RATE
Important Instrument Parameters : 1
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON DENSITY
Instrument Parameter Name : ELECTRON CURRENT
Important Instrument Parameters : 1
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON TEMPERATURE
Instrument Parameter Name : ELECTRON RATE
Important Instrument Parameters : 1
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON TEMPERATURE
Instrument Parameter Name : ELECTRON CURRENT
Important Instrument Parameters : 1
Processing
==========
Processing History
------------------
Source Data Set ID : VG2-PLS
Software : UNK
Product Data Set ID : VG2-S-PLS-5-ELE-PAR-96.0SEC
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