Data Set Information
|
| DATA_SET_NAME |
VG2 NEP LECP RESAMPLED SUMMARY SCAN AVERAGED 24SEC V1.0
|
| DATA_SET_ID |
VG2-N-LECP-4-SUMM-SCAN-24SEC-V1.0
|
| NSSDC_DATA_SET_ID |
|
| DATA_SET_TERSE_DESCRIPTION |
|
| DATA_SET_DESCRIPTION |
Description of the PDS LECP Neptune Scan data. This data consists of resampled data from the Low EnergyCharged Particle (LECP) Experiment on the Voyager 2 Spacecraftfor the period when Voyager 2 was in the vicinity of the planetNeptune. The period covered is 1989-08-24T00:00:00.000 SCET to1989-08-27T00:00:00.000 SCET. This data approximates a time seriesof charged particle fluxes from a selection of channels availablefrom the instrument. The word approximates is used becausethe angle scanning modes of the instrument complicates thenature of the data. At times the instrument mechanically scans,and at times it is fixed to look at a specific direction.With the type of data given here, the fluxes are angle averagedfor those time periods when the instrument is scanning, and aretime averaged over an arbitrary period (12 or 24 sec, see below)for the periods when the detectors are stationary. The angleaveraged records represent periods of time equal to 48 or 96sec (see below). This kind of data presentation has been calledthe LECP Scan data. Another form that is also available isthe LECP Step data that gives the angle distributions sampledduring the scanning periods. Three scanning situations occurred during the time of thisdata. They are: 1) continuous 48 sec stepping (48 seconds foreach of 8 look directions for a total of 6.4 minutes per scan;note that sector 8 is shielded with 2 mm Al), 2) a specialNeptune scan cyclic with the following sequence: 7, scan, 1, scan,7, scan, scan, repeat; where the 7 and the 1 represent 5.2minute periods when the instrument is fixed in sectors 7 or 1,respectively, and where the word scan represents a periodof scanning (6 sec stepping for a total scan time of 48 sec);and 3) periods when the detectors are fixed for more extendedperiods in sector 7 (periods bracketing the ring plane crossings).For this Neptune Scan data, the 6.4 minute scan records duringstepping mode (1) have been time averaged to 12.8 minute records.Also, during stepping mode (2), the double scans that have nofixed periods between them have been averaged together intoa single (96 sec) record. The single scans represent 48 secrecords. The schedule for the three stepping modes is asfollows: prior to day 236/1600 SCET: Mode (1) 236/1600 to 237/0239: Mode (2) 237/0239 to 237/0319: Mode (3) 237/0319 to 237/0503: Mode (2) 237/0503 to 237/0554: Mode (3) 237/0554 to 238/0400: Mode (2) after 237/0400: Mode (1)Obviously these stepping mode changes, and the angle sampleswitching that occurs during stepping mode (2), gives the dataa disjointed appearance. Two channel sample modes also occurred during the Neptuneencounter. These two modes affect this data set only by changingthe primary record time length for the LECP Experiment Data Records(EDR's). These time lengths have, in turn, been utilized for theaveraging times of this data set for non-stepping periods. Theschedule is: prior to day 237/0200 SCET: Far Encounter (24 sec records) 237/0200 to 237/0551: Near Encounter (12 sec records) after 237/0551: Far Encounter (24 sec records) The LECP channels utilized with this data set are: EB01: electrons, 22 to 35 keV EB02: electrons, 35 to 61 keV EB03: electrons, 61 to 112 keV EB04: electrons, 112 to 183 keV EG06-EG07: electrons, 252 to 480 keV EG07-EG08: electrons, 480 to 853 keV EG08-EG09: electrons, 853 to 1200 keV PL01: ions, 28 to 43 keV PL02: ions, 43 to 80 keV PL03: ions, 80 to 137 keV PL04: ions, 137 to 215 keV PL05: ions, 215 to 540 keV PL06: ions, 540 to 990 keV PL07: ions, 990 to 2140 keV PL08: ions, 2140 to 3500 keVPlease note that 3 of the electron channels are derived from4 of the instrumental channels by taking differences betweenadjacent (in energy) channels. The channel data is given in units of intensity:counts/(cm^2.sec.str.keV). For the ions, it has been assumedthat they consist only of protons. Intensity is derived fromthe raw count rates via the relation: I = CR/(eG.(E2-E1),where eG is geometric factor times detector efficiency, and(E2-E1) is the band pass of the channel in energy. The protonvalues of these parameters were used in deriving the intensitiesfor this data set. To obtain the Intensities under the assumptionthat some other mass species dominates, one must convert backto count rate (CR) utilizing the proton parameters, and thenconvert to intensity using the parameters corresponding to themass species in question. The parameters can be found inTable 1 of Krimigis et al. (Journal of Geophysical Research,V. 86, page 8227, 1981) The corresponding parameters for electronscan be found in Mauk et al. (Journal of Geophysical Research,V. 92, page 15283, 1987). Prior to the conversion to intensity,the count rates have been corrected for: (1) Background,(2) electron contamination of the lower energy ion channels, and(3) solar UV contamination of the lowest energy ion channel. The uncertainty parameters given with the data associated witheach channel (expressed as a percent) is the largest of thetwo quantities: (i) one standard deviation Poisson statisticalerror, and (ii) a percentage assigned by the data supplierbased on the amount of contamination correction that has beenperformed on each data channel. Also supplied with each record of this data set is thefraction of the data accumulations that correspond to eachof the 8 angle sectors. For example, during a sector 7 stowperiod, this number will be 1.0 for sector 7 and 0.0 for allof the other sectors. A sector 9 has also been definedcorresponding to those accumulations with no known sectorassignment. Additionally supplied for each data channel a one bit codethat tells whether that channel had any accumulations atall associated with it (1 = yes; 0 = no). This code must beused to distinguish between accumulations that yielded no countsand situations where the channel simply had no accumulations(results in Intensity = 0.0). SAMPLING_PARAMETER_NAME = TIME SAMPLING_PARAMETER_RESOLUTION = 24.0 MINIMUM_SAMPLING_PARAMETER = N/A MAXIMUM_SAMPLING_PARAMETER = N/A SAMPLING_PARAMETER_INTERVAL = 24.0 MINIMUM_AVAILABLE_SAMPLING_INT = 6.0 SAMPLING_PARAMETER_UNIT = SECOND DATA_SET_PARAMETER_NAME = PARTICLE FLUX INTENSITY NOISE_LEVEL = N/A DATA_SET_PARAMETER_UNIT = COUNTS/(CM**2*SECOND*STERRADIAN*KEV)
|
| DATA_SET_RELEASE_DATE |
1991-09-01T00:00:00.000Z
|
| START_TIME |
1989-08-24T12:00:00.000Z
|
| STOP_TIME |
1989-08-27T12:00:00.000Z
|
| MISSION_NAME |
VOYAGER
|
| MISSION_START_DATE |
1972-07-01T12:00:00.000Z
|
| MISSION_STOP_DATE |
N/A (ongoing)
|
| TARGET_NAME |
NEPTUNE
|
| TARGET_TYPE |
PLANET
|
| INSTRUMENT_HOST_ID |
VG2
|
| INSTRUMENT_NAME |
LOW ENERGY CHARGED PARTICLE
|
| INSTRUMENT_ID |
LECP
|
| INSTRUMENT_TYPE |
CHARGED PARTICLE ANALYZER
|
| NODE_NAME |
planetary plasma interactions
|
| ARCHIVE_STATUS |
ARCHIVED
|
| CONFIDENCE_LEVEL_NOTE |
Confidence note for the PDS Neptune LECP Scan data. High quality data is available from the LECP instrumentthroughout the time period addressed with this data set.The data is subject to errors associated with Poissonstatistics and associated with various kinds and levels ofcontamination. The known contaminations are: i) penetratingbackground, ii) Solar UV contamination within the lowest energyion channel when the detector faces sunward, and iii) electroncontamination of the lower energy ion channels (the contaminatingelectrons are measured). Corrections have been made to the datain attempts to remove the effects of these contaminations. An error parameter is given for each particle intensityvalue given in the data set. This error is expressed as apercentage. This number is the larger of the followingitems: 1) the one standard deviation Poisson error, and 2) avalue assigned by the data supplier associated with the degreeof correction that was required with regard to the contaminationslisted above. Missing data is indicated with a binary flag associatedwith each energy channel. Each channel's flag will read 1if at least one instrumental accumulation occurred for thatchannel and for that record. The flag reads 0 for noaccumulations. This parameter must be utilized to distinguishbetween accumulations that yielded no counts, and the situationwhere there simply were no accumulations (the error parameterreads 100 for both cases).
|
| CITATION_DESCRIPTION |
Krimigis, S. M., Mauk, B. H., Armstrong, T. P., VG2-N-LECP-4-SUMM-SCAN-24SEC-V1.0, VG2 NEP LECP RESAMPLED SUMMARY SCAN AVERAGED 24SEC V1.0. NASA Planetary Data System, 1991.
|
| ABSTRACT_TEXT |
This data consists of resampled data from the Low EnergyCharged Particle (LECP) Experiment on the Voyager 2 Spacecraftfor the period when Voyager 2 was in the vicinity of the planetNeptune. The period covered is 1989-08-24T00:00:00.000 SCET to1989-08-27T00:00:00.000 SCET. This data approximates a time seriesof charged particle fluxes from a selection of channels availablefrom the instrument. The word approximates is used becausethe angle scanning modes of the instrument complicates thenature of the data. At times the instrument mechanically scans,and at times it is fixed to look at a specific direction.With the type of data given here, the fluxes are angle averagedfor those time periods when the instrument is scanning, and aretime averaged over an arbitrary period (12 or 24 sec, see below)for the periods when the detectors are stationary.
|
| PRODUCER_FULL_NAME |
DR. BARRY MAUK
|
| SEARCH/ACCESS DATA |
Planetary Plasma Interactions Website
|
|
.png)
.png)
