Data Set Overview : Data Set Description -------------------- This far 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 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 0.4 second rate 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. V2YYDOY{A,B,...,H}MG{01,02, ..., 16}.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 are listed as below: ------------------------------------------------------- rate channel names group in # the rate group ------------------------------------------------------- 1 PL01 PL02 PL03 EB04 EBP04 2 EB01 EBP01 EB02 EBP02 EB03 EBP03 EG06 3 A39 A33 P32 P31 4 EG07 EG08 EG09 EB05 EBP05 5 P1 E44 A3 P10 6 PL04 PL08 AR E0 E1 E2 E3 E4 E5 AL P16 7 P11 P23 P27 A4 8 A46 A13 M47 A17 A28 M38 9 M35 PL05 PL06 PL07 10 E45 ALAR? A12 A24 11 M34 L5 L18 L14 12 M6 M7 M19 H36 13 H8 H43 M25 H9 14 M29 H22 H26 H30 15 AL01 AL02 E37 H21 16 M15 M20 ------------------------------------------------------- Far encounter data file has the format described as: : name data type description ------------------------------------------------------------------ TIME char time in the format 'yyyy-mm-dd hh:mm:ss.sss ' STEP int step position (0-7) MOTOR_MOVEMENT int motor movement: 0 - no movement, 1 - movement during accumulation CH1_RATE real counts measured during accumulation interval ACC_TIME_CH1 real accumulation time for CH1 CH2_RATE real counts measured during accumulation interval ACC_TIME_CH2 real accumulation time for CH2 ... ... ... CHn_RATE real counts measured during accumulation interval ACC_TIME_CHn real accumulation time 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 : 0.400000 Sampling Parameter Interval : 0.400000 Data Set Parameter Unit : COUNTS Noise Level : 0.000000 Sampling Parameter Unit : SECOND 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 : 0.400000 Sampling Parameter Interval : 0.400000 Data Set Parameter Unit : COUNTS Noise Level : 0.000000 Sampling Parameter Unit : SECOND 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 : ION RATE Instrument Parameter Name : ION RATE Important Instrument Parameters : 1

Confidence Level Overview : At all times during this planetary encounter there exist data in this data set that can be rated with the highest confidence level. However, some of the channels of data are contaminated by various kinds and various levels of contaminations. It is therefore imperative, in using this data set, that the contamination tables within the catalog be examined. Also, not all kinds of contamination have been fully documented. When in doubt the data supplier must be contacted. Some channels are subject to serious contaminations, and many of these contaminations cannot be removed except with a region- by-region analysis, which has not been done for this data. Thus, to use this data it is absolutely vital that the contamination types ('CONTAMINATION_ID' , 'CONTAMINATION_DESC') and the levels of contamination ('DATA_QUALITY_ID' corresponding to the definitions 'DATA_QUALITY_DESC') be carefully examined for all regions of study. A dead time correction procedure has been applied in an attempt to correct the linear effects of detector overdrive (pulse-pileup). This procedure does not fix severely overdriven detectors. A procedure is available for correcting Voyager 2 LECP electron contamination of low energy ion channels, but its effectiveness has been evaluated only for the Uranus data set. Thus, corrections have been applied only to the Uranus data set. Missing Data Flag : Any data column whose value is NULL is a missing data value.