| DATA_SET_DESCRIPTION |
Data Set Overview
=================
Data Set Description
--------------------
This far encounter step data set consists of the counting
rate and flux data for electrons and ions from the Low Energy
Charged Particle (LECP) experiment on Voyager 2 while the
spacecraft was within the vicinity of Neptune. This instrument
measures the intensities of in-situ charged particles
( >13 keV electrons and >24 keV ions) with various levels of
discrimination based on energy range and mass species. A
subset of almost 100 LECP channels are included in this data
set. The LECP data are globally calibrated to the extent
possible. During Neptune far encounter, the entire LEPT
(Low Energy Particle Telescope) and part of the LEMPA (Low
Energy Magnetospheric Particle Analyzer) subsystems were
turned on for data collection. Particles include electrons,
protons, alpha particles, and light, medium, and heavy nuclei
particles. The far encounter data are 12.8 minute rate and flux
measurements within 1/8 of the LECP instrumental motor rotation
period (the angular scanning periods, or step period).
The LECP instrument has a rotating head for obtaining angular
anisotropy measurements of the medium energy charged particles.
A gear-drive motor steps through eight equal angular sectors
per revolution for data collection. The cycle time for the
rotation is 48 minutes or 25.6 minutes during cruise mode,
and 192 second or 48 second during the planetary encounter.
The data were originally collected in the form of 'rates',
which were not always converted into 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 is covered by a 2 mm
Aluminium sunshield and used for data calibration).
2) Divide the background corrected rate by the channel
geometric factor and by the energy bandpass of the channel.
To determine the energy bandpass, one must judge the mass
species of the detected particles (for ions but not for
electrons). The energy band passes are given in the form
of '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, which
gives 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 bandpasses 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 in the
unit of 'counts/(cm**2 sr sec keV)'. LECP data can
also be in the form of flux, whose unit is
'cm**-1 sr**-1 sec**-1'.
Far Encounter Channel Definitions for Voyager 2 LECP
CH CH LOW HIGH MEAN GEOMETRIC CH
Num NAME (MeV/N) (MeV/N) (Mev/N) FACTOR LOGIC
cm**2 sr DEFINITIN
--------------------------------------------------------
1 EB01 0.013 0.035 0.020 0.00200
2 EBD1 0.013 0.035 0.020 0.00200
3 EB02 0.035 0.061 0.045 0.00200
4 EBD2 0.035 0.061 0.045 0.00200
5 EB03 0.061 0.112 0.090 0.00200
6 EBD3 0.061 0.112 0.090 0.00200
7 EB04 0.112 0.183 0.120 0.00200
8 EBD4 0.112 0.183 0.120 0.00200
9 EB05 0.183 0.500 0.200 0.00200
10 EBD5 0.183 0.500 0.200 0.00200
11 EG06 0.252 2.000 0.250 0.00200
12 EG07 0.480 2.000 0.500 0.00200
13 EG08 0.853 2.000 0.900 0.00200
14 EG09 2.100 5.000 2.000 0.00200
15 E44 0.350 1.500 0.500 1.31000
16 E45 2.000 100.000 2.000 1.31000
17 E37 6.000 100.000 6.000 1.31000
18 PL01 0.024 0.048 0.025 0.12000
19 PL02 0.048 0.080 0.050 0.12000
20 PL03 0.080 0.137 0.100 0.12000
21 PL04 0.137 0.215 0.150 0.12000
22 PL05 0.215 0.540 0.250 0.12000
23 PL06 0.540 0.990 0.600 0.12000
24 PL07 0.990 2.140 1.000 0.12000
25 PL08 2.140 3.500 2.500 0.12000
26 P32 0.330 0.610 0.350 0.09750 E0E2(E3)
27 P1 0.520 1.450 0.600 0.44100 E1E2(E3)
28 P10 4.400 11.400 5.000 0.53900 E2E3(E4)
29 P11 11.400 20.000 12.000 0.53900 E2E3(E4)
30 P16 3.040 17.000 5.000 1.50000 E5E4(E3)
31 P23 22.000 30.000 25.000 1.31000 E5E4E3(E2)
32 P27 37.000 89.000 50.000 1.20000 E5E4E3E2
33 P31 213.000 1000.000 250.000 1.31000 E4E3
34 A39 0.091 0.233 0.100 0.09750 E0(E2)
35 A33 0.230 0.480 0.350 0.09750 E0E2(E3)
36 A46 0.147 2.000 0.600 0.44100 'D1F1,CA'
37 A3 0.420 1.700 0.600 0.44100 E1E2(E3)
38 A4 1.800 4.000 2.500 0.44100 E1E2(E3L12)
39 A12 4.200 7.800 5.000 0.53900 E2E3(E4L23)
40 A13 7.800 20.000 15.000 0.53900 E2E3(E4L23)
41 A17 3.000 58.000 5.000 1.50000 E5E4(E3L54)
42 A24 22.000 30.000 25.000 1.31000 E5E4E3(E2)
43 A28 31.000 56.000 50.000 1.20000 E5E4E3E2
44 AL01 1.040 1.850 1.000 0.12000 CALC.
45 AL02 1.850 3.700 2.500 0.12000 CALC.
46 M34 0.230 0.440 0.200 0.09750 E0E2
47 L5 0.710 5.600 1.500 0.44100 E1E2(E3L12)
48 L14 5.800 28.000 6.000 0.53900 E2E3(E4L23)
49 L18 3.900 20.000 5.000 1.50000 E5E4(E3L54)
50 M38 0.060 0.200 0.100 0.09750 E0(E2)
51 M35 0.200 0.340 0.250 0.09750 E0E2(E3)
52 M47 0.124 14.300 0.250 0.44100 D1F2
53 M6 0.470 5.200 0.500 0.44100 E1E2(E3L12)
54 M7 5.200 8.200 6.000 0.44100 E1E2(E3L12)
55 M15 8.600 40.000 15.000 0.53900 E2E3(E4L23)
56 M19 6.000 9.200 6.000 1.50000 E5E4(E3L54)
57 M20 9.600 42.000 15.000 1.50000 E5E4(E3L54)
58 M25 44.000 61.000 50.000 1.31000 E5E4E3(E2)
59 M29 69.000 270.000 70.000 1.20000 E5E4E3E2
60 H36 0.099 0.140 0.100 0.09750 E0(E2)
61 H8 0.280 1.900 0.350 0.44100 E1E2(E3)
62 H9 2.000 12.000 2.000 0.44100 E1E2(E3)
63 H43 11.800 74.000 15.000 0.53900 E2E3(E4)
64 H21 8.200 17.000 10.000 1.50000 E5E4(E3L54)
65 H22 18.000 82.000 25.000 1.50000 E5E4(E3L54)
66 H26 86.000 120.000 100.000 1.31000 E5E4E3
67 H30 127.000 1000.000 150.000 1.20000 E5E4E3E2
68 AR SINGLES
69 E0 SINGLES
70 E1 SINGLES
71 E2 SINGLES
72 E3 SINGLES
73 E4 SINGLES
74 E5 SINGLES
75 AL SINGLES
76 ALAR SINGLES
--------------------------------------------------------
Far encounter data are stored in files for channels from
different rate groups indicated by the file names, e.g.
V2YYDOYS{Rate_Group_Number}.CSV
------- -----------------
| | | |
| | | rate group # for far encounter
| | | 1-16, 22-35
| | |
| | 3-digit day of year
| |
| 2-digit year
|
Voyager 2
Rate group definitions are listed as below:
--------------------------------------------------------------------
Rate
Group CH# CH# CH# CH# CH# CH# Descriptions
#
--------------------------------------------------------------------
1 18 19 20 21 22 PL01,2,3,4,5 Rates
2 23 24 25 44 45 PL06,7,8,AL01,2 Rates
3 1 3 5 7 9 EB01,2,3,4,5 Rates
4 2 4 6 8 10 EB'01,2,3,4,5 Rates
5 11 12 13 14 EG06,7,8,9 Rates
6 34 50 36 52 E0 (E1) , D1F1, D1F2 Rates
7 26 35 46 51 60 E0 E2 (E3) Rates
8 27 28 29 53 54 Protons, Mediums Rates
9 37 38 47 61 62 Alphas, L Nuclei, H Nuclei Rates
10 39 40 48 55 63 Alphas, L Nuclei, H Nuclei Rates
11 15 16 17 33 E44, E45, E37, P31 Rates
12 30 31 42 58 66 E5 E4 (E3) Rates
13 32 43 59 67 E5 E4 E3 E2 Rates
14 41 49 56 57 64 65 E5 E4 (E3) Rates
15 68 75 76 74 73 Singles Rates
16 69 70 71 72 Singles Rates
17 83 84 85 97 98 99 Pd09,10,11, A d03,04,Z d01 Rates
18 80 81 82 94 95 96 Pd'09,10,11, A d'03,04,Z d'01 Rates
19 77 88 89 90 ESA0, PSA1, PSA2, PSA3 Rates
20 78 91 92 93 ESB0, PSB1, PSB2, PSB3 Rates
21 79 86 87 AB10, AB12, AB13 Rates
22 18 19 20 21 22 PL01,2,3,4,5 Fluxes
23 23 24 25 44 45 PL06,7,8,AL01,2 Fluxes
24 1 3 5 7 9 EB01,2,3,4,5 Fluxes
25 2 4 6 8 10 EB'01,2,3,4,5 Fluxes
26 11 12 13 14 EG06,7,8,9 Fluxes
27 34 50 36 52 E0 (E1) , D1F1, D1F2 Fluxes
28 26 35 46 51 60 E0 E2 (E3) Fluxes
29 27 28 29 53 54 Protons, Mediums Fluxes
30 37 38 47 61 62 Alphas, L Nuclei, H Nuclei Fluxes
31 39 40 48 55 63 Alphas, L Nuclei, H Nuclei Fluxes
32 15 16 17 33 E44, E45, E37, P31 Fluxes
33 30 31 42 58 66 E5 E4 (E3) Fluxes
34 32 43 59 67 E5 E4 E3 E2 Fluxes
35 41 49 56 57 64 65 E5 E4 (E3) Fluxes
36 83 84 85 97 98 99 Pd09,10,11, A d03,04,Z d01 Fluxes
37 80 81 82 94 95 96 Pd'09,10,11, A d'03,04,Z d'01 Fluxes
38 77 88 89 90 ESA0, PSA1, PSA2, PSA3 Fluxes
39 78 91 92 93 ESB0, PSB1, PSB2, PSB3 Fluxes
40 79 86 87 AB10, AB12, AB13 Fluxes
--------------------------------------------------------------------
Far encounter data file has the format described as:
==================================================================
name data type description
------------------------------------------------------------------
START_TIME char time in the format 'yyyy-mm-dd hh:mm:ss.sss '
STOP_TIME char time in the format 'yyyy-mm-dd hh:mm:ss.sss '
SECTOR int sector position (1-8)
SCAN_DIR int 1: for increasing; -1: for decreasing
CH1_RATE/FLUX real counting rate/flux for CH1
CH1_RATE/FLUX_UNCERTAINTY
real uncertain of the counting rate/flux for CH1
CH2_RATE/FLUX real counting rate/flux for CH2
CH2_RATE/FLUX_UNCERTAINTY
real uncertain of the counting rate/flux for CH2
...
...
...
CHn_RATE/FLUX real counting rate/flux for CHn
CHn_RATE/FLUX_UNCERTAINTY
real uncertain of the counting rate/flux for CHn
where n is determined by the above table given rate group number.
Parameters
==========
Processing Level Id : 3
Software Flag : Y
Processing Start Time : UNK
Electron Rate
-------------
Sampling Parameter Name : TIME
Data Set Parameter Name : ELECTRON RATE
Sampling Parameter Resolution : 6.400000
Sampling Parameter Interval : 6.400000
Data Set Parameter Unit : COUNTS/SECOND
Noise Level : 0.000000
Sampling Parameter Unit : MINUTE
Sampling Parameter Name : TIME
Data Set Parameter Name : ELECTRON FLUX
Sampling Parameter Resolution : 6.400000
Sampling Parameter Interval : 6.400000
Data Set Parameter Unit : CM**-2 SR**-2 SEC**-1
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 : 6.400000
Sampling Parameter Interval : 6.400000
Data Set Parameter Unit : COUNTS/SECOND
Noise Level : 0.000000
Sampling Parameter Unit : MINUTE
Sampling Parameter Name : TIME
Data Set Parameter Name : ION FLUX
Sampling Parameter Resolution : 6.400000
Sampling Parameter Interval : 6.400000
Data Set Parameter Unit : CM**-2 SR**-2 SEC**-1
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 : ELECTRON RATE
Instrument Parameter Name : ELECTRON RATE
Important Instrument Parameters : 1
Instrument Host ID : VG2
Data Set Parameter Name : ELECTRON FLUX
Instrument Parameter Name : ELECTRON FLUX
Important Instrument Parameters : 1
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 : ION FLUX
Instrument Parameter Name : ION FLUX
Important Instrument Parameters : 1
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