• Data Set Overview

• =================

• Data Set Description

• ====================

This Near Encounter Data Set consists of Electron and Ion Counting Rate Data from the Low Energy Charged Particle (LECP) Experiment on Voyager 2 while the Spacecraft was within the very close Vicinity of Saturn.

The LECP 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, Mass Species, and angular Arrival Direction. A Subset of almost 100 LECP Channels are included in this Data Set. The LECP Data are globally calibrated to the extent possible (see below).

During the Saturn Near Encounter, the Low Energy Magnetospheric Particle Analyzer (LEMPA) Subsystem was turned on for Data Collection. Particles include Low Energy Electrons, Protons, Alpha Particles, Medium Energy Protons and Ions, High Energy and High Intensity Protons, Electrons, Alpha Particles, and Z≥2 Nuclei Particles. The Near Encounter Data are 0.4 s Rate Measurements within one eighth of the LECP instrumental Motor Rotation Period (the angular Scanning Period 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 25.6 min or 48 min during Cruise Mode, and 48 s or 192 s during the Planetary Encounter.

The Data were originally collected in the Form of "Rate" Data which were not always 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 the Background. Both the Mass Species and the 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. The 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 is used for Data Calibration).
• 2. Divide the Background-corrected Rate by the Geometric Factor of the Channel and by the Energy Bandpass of the Channel.

The Geometric Factor is found in the Entry for CHANNEL_GEOMETRIC_FACTOR as associated with the CHANNEL_ID of each Channel.

To determine the Energy Bandpass, one must judge the Mass Species of the detected Particles (for Ions but not for Electrons). The Energy Bandpasses are given in the Entries MINIMUM_INSTRUMENT_PARAMETER and MAXIMUM_INSTRUMENT_PARAMETER in Table FPLECPENERGY, and are given in the Form of "Energy per 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 the Entries for MINIMUM_INSTRUMENT_PARAMETER and MAXIMUM_INSTRUMENT_PARAMETER in Table FPLECPCHANZ, which give the Minimum and Maximum "Z" Value accepted. Note that 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., Krimigis et al., (1979a)). The final Product of these Instructions will be the Particle Intensity in Units of counts/(cm^2 s sr keV). LECP Data can also be expressed in the Form of Flux, whose Units are (cm^2 s sr)^-1.

• Near Encounter Channel Definitions for Voyager 2 LECP
• =====================================================

+-----------------------------------------------------------------------------------------------------------------+
| CH Num | CH Name | Low (MeV/n) | High (MeV/n) | Mean (MeV/n) | Geometric Factor (cm^2 sr) | CH Logic Definition |

| 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 | |
| 44 | AL01 | 1.040 | 1.850 | 1.000 | 0.12000 | CALC. |
| 45 | AL02 | 1.850 | 3.700 | 2.500 | 0.12000 | CALC. |
| 77 | ESA0 | 2.500 | 99.999 | 2.500 | 0.49350 | A-B Coincidence |
| 78 | ESB0 | 8.500 | 99.999 | 8.500 | 0.94620 | B 4π sr |
| 79 | AB10 | 8.500 | 99.999 | 8.500 | 0.05040 | A-B Coincidence |
| 80 | DP09 | 0.285 | 5.020 | 0.250 | 0.00084 | Delta' |
| 81 | DP10 | 0.480 | 2.580 | 0.600 | 0.00084 | Delta' |
| 82 | DP11 | 0.725 | 1.640 | 1.000 | 0.00084 | Delta' |
| 83 | PD09 | 0.285 | 5.250 | 0.250 | 0.00260 | Delta |
| 84 | PD10 | 0.480 | 2.720 | 0.600 | 0.00260 | Delta |
| 85 | PD11 | 0.725 | 1.580 | 1.000 | 0.00260 | Delta |
| 86 | AB12 | 54.000 | 87.300 | 50.000 | 0.05040 | A-B Coincidence |
| 87 | AB13 | 87.300 | 152.000 | 100.000 | 0.05040 | A-B Coincidence |
| 88 | PSA1 | 15.800 | 158.000 | 15.000 | 0.49350 | A 2π sr |
| 89 | PSA2 | 15.800 | 49.000 | 25.000 | 0.49350 | A 2π sr |
| 90 | PSA3 | 16.300 | 26.200 | 25.000 | 0.49350 | A 2π sr |
| 91 | PSB1 | 54.000 | 174.000 | 50.000 | 0.94620 | B 4π sr |
| 92 | PSB2 | 54.000 | 87.300 | 50.000 | 0.94620 | B 4π sr |
| 93 | PSB3 | 54.000 | 59.000 | 50.000 | 0.94620 | B 4π sr |
| 94 | DA03 | 0.480 | 2.450 | 0.600 | 0.00084 | Delta' |
| 95 | DA04 | 0.780 | 1.410 | 1.000 | 0.00084 | Delta' |
| 96 | DZ01 | 0.405 | 18.800 | 0.600 | 0.00084 | Delta' |
| 97 | AD03 | 0.480 | 2.580 | 0.600 | 0.00260 | Delta |
| 98 | AD04 | 0.780 | 1.480 | 1.000 | 0.00260 | Delta |
| 99 | ZD01 | 0.400 | 19.800 | 0.600 | 0.00260 | Delta |
+-----------------------------------------------------------------------------------------------------------------+

• Near Encounter Data are stored in Files for Channels from different Rate Groups as indicated by the File Name
• =============================================================================================================

+-----------------------------------------+

| V2YYDOY{A,B,...,H}NG0{1,2, ..., 9}.CSV |

| ------- --------- ----------- |
| ! ! ! ! ! |
| ! ! ! ! Rate Group Number |
| ! ! ! ! |
| ! ! ! Starting Time A: 00:00:00 |
| ! ! ! B: 03:00:00 |
| ! ! ! C: 06:00:00 |
| ! ! ! D: 09:00:00 |
| ! ! ! E: 12:00:00 |
| ! ! ! F: 15:00:00 |
| ! ! ! G: 18:00:00 |
| ! ! ! H: 21:00:00 |
| ! ! ! |
| ! ! 3-Digit Day of Year |
| ! ! |
| ! 2-Digit Year |
| ! |
| Voyager 2 |
+-----------------------------------------+

• Rate Group Definitions
• ======================

+--------------------------------------------------------------------+
| Rate Group Number | Channel Names in the Rate Group |

| 1 | PL01 PL02 PL03 EB04 EBP04 |
| 2 | EB01 EBP01 EB02 EBP02 EB03 EBP03 EG06 |
| 3 | PD09 DP09 PD10 DP10 PD11 DP11 AD03 DA03 |
| 4 | EG07 EG08 EG09 EB05 EBP05 |
| 5 | PSA3 PSB3 AB12 AB13 |
| 6 | PL04 ZD01 DZ01 ESA0 ESB0 |
| 7 | PSA1 PSB1 PSA2 PSB2 |
| 8 | AL01 AL02 PL08 AD04 DA04 |
| 9 | AB10 PL05 PL06 PL07 |
+--------------------------------------------------------------------+