| DATA_SET_DESCRIPTION |
Data Set Description
====================
Version 1.1
-----------
This version 1.1 data set replaces the version 1.0 data set
(DATA_SET_ID = VG2-J-LECP-4-15MIN) previously archived with
the PDS. Data records from the version 1.0 data set provided
data for each of 8 sectors, plus the average for all sectors
in a separate record for each channel. This resulted in 9
repeated times per channel. Data records for the version 1.1
data set provide all data for a given channel and time period
(8 sectors, plus the average for all sectors) in a single
record. Other changes to this version include upgrading of the
associated labels and templates to PDS version 3.4 compliance,
modification of the time formats and flag values.
Data Set Description
--------------------
This data set consists of resampled data from the Low Energy
Charged Particle (LECP) experiment on Voyager 2 while the
spacecraft was in the vicinity of Jupiter. This instrument
measures the intensities of in-situ charged particles (>26 keV
electrons and >30 keV ions) with various levels of
discrimination based on energy, mass species, and angular
arrival direction. A subset of almost 100 LECP channels are
included with this data set. The LECP data are globally
calibrated to the extent possible (see below) and they are
time averaged to about 15 minute time intervals with the exact
beginning and ending times for those intervals matching the
LECP instrumental cycle periods (the angular scanning periods).
The LECP instrument has a rotating head for obtaining angular
anisotropy measurements of the medium energy charged particles
that it measures. The cycle time for the rotation if variable,
but during encounters it is always faster than 15 minutes.
Thus, the full angular anisotropy information is preserved with
this data. The data is in the form of 'rate' data which has not
been converted to the usual physical units. The reason is that
such a conversion would depend on uncertain determinations such
as the mass species of the particles and the level of
background. Both mass species and background are generally
determined from context during the study of particular regions.
To convert 'rate' to 'intensity' for a particular channel one
performs the following tasks: 1) Decide on the level of
background contamination and subtract that off the given rate
level. Background is to be determined from context and from
making use of sector 8 rates (sector 8 has a 2 mm Al shield
covering it). 2) Divide the background corrected rate by the
channel geometric factor and by the energy bandpass of the
channel. The geometric factor is found in entry
'CHANNEL_GEOMETRIC_FACTOR' as associated with each channel
'CHANNEL_ID'. To determine the energy bandpass, one must
judge the mass species of the of the detected particles (for
ions but not for electrons). The energy band passes are given
in entries 'MINIMUM_INSTRUMENT_PARAMETER' and
'MAXIMUM_INSTRUMENT_PARAMETER' in table 'FPLECPENERGY', and
are given in the form 'energy/nucleon'. For channels that
begin their names with the designations 'CH' these bandpasses
can be used on mass species that are accepted into that
channel (see entries 'MINIMUM_INSTRUMENT_PARAMETER' AND
'MAXIMUM_INSTRUMENT_PARAMETER' in table 'FPLECPCHANZ', which
give the minimum and maximum 'Z' value accepted -- these
entries are blank for electron channels). For other channels
the given bandpass refers only to the lowest 'Z' value
accepted. The and passes for other 'Z' values are not all
known, but some are given in the literature (e.g.
[KRIMIGISETAL1979A]). The final product of these instructions
will be the particle intensity with the units:
counts/(cm^2 str sec keV).
Parameters
==========
Electron Rate
-------------
Sampling Parameter Name : TIME
Data Set Parameter Name : ELECTRON RATE
Sampling Parameter Resolution : 15.000000
Sampling Parameter Interval : 15.000000
Data Set Parameter Unit : COUNTS/SECOND
Noise Level : 0.000000
Sampling Parameter Unit : MINUTE
A measured parameter equaling the number of electrons hitting
a particle detector per specified accumulation interval. The
counted electrons may or may not be discriminated as to their
energies (e.g. greater than E1, or between E1 and E2).
Ion Rate
--------
Sampling Parameter Name : TIME
Data Set Parameter Name : ION RATE
Sampling Parameter Resolution : 15.000000
Sampling Parameter Interval : 15.000000
Data Set Parameter Unit : COUNTS/SECOND
Noise Level : 0.000000
Sampling Parameter Unit : MINUTE
A measured parameter equaling the number of ions striking a
particle detector per specified accumulation interval. The
counted ions may or may not be discriminated as to their
energies (e.g. energy/nucleon or energy/charge between E1 and
E2 or greater than E1) and/or as to their ion composition
(atomic number Z or mass number greater than Z1 or M1, or
between Z1 and z2 or M1 and M2).
Source Instrument Parameters
============================
Instrument Host ID : VG2
Data Set Parameter Name : ION RATE
Instrument Parameter Name : ION RATE
Important Instrument Parameters : 1
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON RATE
Instrument Parameter Name : ELECTRON RATE
Important Instrument Parameters : 1
Processing
==========
Processing Level Id : 4
Software Flag : Y
Processing Start Time : 1988-08-01
Processing History
------------------
Source Data Set ID : VG2-J-LECP-2-
Software : PFAT:VGER
Product Data Set ID : VG2-J-LECP-4-15MIN
Software 'PFAT:VGER'
--------------------
Software Name : PFAT:VGER
Software Type : PIN
Software Release Date : N/A
Node ID : N/A
Cognizant Engineer : N/A
Software Access Description : N/A
Data Coverage
=============
Filename Records Start Stop
-------------------------------------------------------------------
Volume ID: VG_1502
SECTOR.TAB 64944 1979-07-02T07:35:11.000Z 1979-08-03T23:30:21.000Z
SECTOR_SUMMARY.TAB 784 1979-07-02T07:00:00.000Z 1979-08-03T22:00:00.000Z
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