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 1 while the spacecraft was within the very close vicinity of Jupiter. This 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. During Jupiter near encounter, the LEMPA (Low Energy Magnetospheric Particle Analyzer) subsystem was turned on for data collection. Particles include low energy electrons, protons, alpha particles, medium energy protons and ions, high energy and intensity protons, electrons, alpha particles, and Z >: nuclei. The near 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'. Near Encounter Channel Definitions for Voyager 1 LECP CH CH LOW HIGH MEAN GEOMETRIC CH Num NAME (MeV/N) (MeV/N) (Mev/N) FACTOR LOGIC cm**2 sr DEFINITIN -------------------------------------------------------- 1 EB01 0.015 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 COINC. 78 ESB0 8.500 99.999 8.500 0.94620 B 4 PI SR 79 AB10 8.500 99.999 8.500 0.05040 A-B COINC. 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 COINC. 87 AB13 87.300 152.000 100.000 0.05040 A-B COINC. 88 PSA1 15.800 158.000 15.000 0.49350 A 2 PI SR 89 PSA2 15.800 49.000 25.000 0.49350 A 2 PI SR 90 PSA3 16.300 26.200 25.000 0.49350 A 2 PI SR 91 PSB1 54.000 174.000 50.000 0.94620 B 4 PI SR 92 PSB2 54.000 87.300 50.000 0.94620 B 4 PI SR 93 PSB3 54.000 59.000 50.000 0.94620 B 4 PI 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 names, e.g. V1YYDOY{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 1 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 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 ------------------------------------------------------- Near 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 : VG1 Data Set Parameter Name : ELECTRON RATE Instrument Parameter Name : ELECTRON RATE Important Instrument Parameters : 1 Instrument Host ID : VG1 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.