Data Set Overview
- Data Set Description
- ===================
This Near Encounter Step Data Set consists of Electron and Ion Counting Rate and Flux Data from the Low Energy Charged Particle (LECP) Experiment on Voyager 1 while the Spacecraft was within the very close Vicinity of Jupiter.
The LECP Instrument measures the Intensities of in situ Charged Particles (>15 keV Electrons and >30 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 (see below).
During the Jupiter 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. The Near Encounter Data are 48 s Rate and Flux Measurements within one eighth 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 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.
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 in the Form of Flux, whose Units are (cm^2 s sr)^-1.
- Near Encounter Channel Definitions for Voyager 1 LECP
- =====================================================
+-----------------------------------------------------------------------------------------------------------------+
| CH Num | CH Name | Low (MeV/n) | High (MeV/n) | Mean (MeV/n) | Geometric Factor (cm^2 sr) | CH Logic Definition |
| 1 | EB01 | 0.015 | 0.037 | 0.020 | 0.00600 | |
| 2 | EBD1 | 0.015 | 0.500 | 0.020 | 0.00012 | |
| 3 | EB02 | 0.037 | 0.061 | 0.045 | 0.00600 | |
| 4 | EBD2 | 0.037 | 0.500 | 0.045 | 0.00012 | |
| 5 | EB03 | 0.070 | 0.112 | 0.090 | 0.00600 | |
| 6 | EBD3 | 0.070 | 0.500 | 0.090 | 0.00012 | |
| 7 | EB04 | 0.130 | 0.183 | 0.120 | 0.00600 | |
| 8 | EBD4 | 0.130 | 0.500 | 0.120 | 0.00012 | |
| 9 | EB05 | 0.200 | 0.500 | 0.200 | 0.00600 | |
| 10 | EBD5 | 0.200 | 0.500 | 0.200 | 0.00012 | |
| 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 | 2.500 | 100.000 | 2.000 | 1.31000 | |
| 17 | E37 | 6.000 | 100.000 | 6.000 | 1.31000 | |
| 18 | PL01 | 0.030 | 0.053 | 0.025 | 0.04020 | |
| 19 | PL02 | 0.053 | 0.085 | 0.050 | 0.04020 | |
| 20 | PL03 | 0.085 | 0.139 | 0.100 | 0.04020 | |
| 21 | PL04 | 0.139 | 0.200 | 0.150 | 0.04020 | |
| 22 | PL05 | 0.200 | 0.550 | 0.250 | 0.04020 | |
| 23 | PL06 | 0.540 | 1.050 | 0.600 | 0.04020 | |
| 24 | PL07 | 1.050 | 2.030 | 1.000 | 0.04020 | |
| 25 | PL08 | 2.030 | 4.010 | 2.500 | 0.04020 | |
| 44 | AL01 | 0.980 | 1.770 | 1.000 | 0.04020 | |
| 45 | AL02 | 1.770 | 4.220 | 2.500 | 0.04020 | |
| 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 indicated by the File Name
- ==========================================================================================================
+-----------------------------------------+
| V1YYDOYS{Rate_Group_Number}.CSV |
| -------- ----------------- |
| ! ! ! ! |
| ! ! ! Rate Group Num, Near Encounter |
| ! ! ! 1-5, 17-21, 23-26, 36-40 |
| ! ! ! |
| ! ! ! |
| ! ! ! |
| ! ! ! |
| ! ! 3-Digit Day of Year |
| ! ! |
| ! 2-Digit Year |
| ! |
| Voyager 1 |
+-----------------------------------------+
- Rate Group Definitions
- ======================
+------------------------------------------------------------------------------------+
| Rate Group Number | 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 |
+------------------------------------------------------------------------------------+