Data Set Overview : This dataset contains Voyager 2 spacecraft position vectors relative to Neptune in minus NLS coordinates. The NLS or Neptune West Longitude System coordinate system is a planetocentric system fixed to Neptune which is rotating with a 16.11 hour period. The NLS coordinate system is defined as follows: - X lies in the equatorial plane of Neptune, positive away from the planet, and through the prime meridian. - Z is parallel to the Neptune spin axis, and, - Y is X x Z (lefthanded) The prime meridian of the this system is defined such that at 1989-08-25T03:56:00.000 the Voyager 2 spacecraft was at 167.7 degrees west longitude. For the PDS archive dataset, the original data archive has been converted to an east longitude (righthanded) coordinate system minus NLS (-NLS). This is achieved by reversing the direction of the Y-axis or in spherical coordinates, subtracting the NLS longitude from 360.0 degrees. The data are provided in units of Neptune radii which was taken to be 24,765km by the Voyager project. Angles are given in degrees. Both cartesian and spherical coordinates are provided. Parameters : Sampling parameter name : time Sampling parameter resolution : 12.0 seconds Minimum sampling parameter : n/a Maximum sampling parameter : n/a Sampling parameter interval : 12.0 seconds Minimum available sampling interval : 12.0 seconds Data set parameter name : position vector Noise level : n/a Data set parameter unit : Neptune radii (24,765km) or degrees Coordinates : Neptune West Longitude System (NLS) Coordinates ----------------------------------------------- Coordinate System Center Name : NEPTUNE Coordinate system Ref Epoch : UNK /* 1989-08-25:03:56:00.000 */ The orientation of Neptune's pole is specified by a right ascension of 298.90 and declination of 42.84 at the time of the encounter, as given in the Jet Propulsion Laboratory's distribution of physical constants dated 11/06/89. Planetary longitudes are based on a 16.11 hour rotation period (Warwick et al., 1989) adopted by the Voyager Project shortly after the encounter. The zero longitude is defined by the requirement that the West Longitude of the spacecraft at 0356 SCET day 237 (near closest approach) be 167.7 NLS; West Longitudes of the Neptune Longitude System (NLS) are simply related to the angle PHI: WLONG : 360. - PHI (degrees) This definition of the zero longitude was adopted by the Voyager Project Steering Group in order to minimize differences in longitudes resulting from changes in the assumed rotation period. Position is given in terms of the following: RANGE (R) - Range from the planet center to the spacecraft in units of Rn where Rn : 24,765km. LATITUDE (LAT) - Spacecraft latitude in degrees. Valid range -90.0 -> +90.0. LONGITUDE (W_LONG) - West longitude where the zero longitude is defined by the requirement that the West Longitude of Voyager 2 at 1989-08-25T03:56:00.00 was 167.7 degrees.

Confidence Level Overview : There is no dataset confidence information archived with this dataset. The data provider has included a flag value which is included in the mag dataset which may reduce confidence in individual vectors due to telemetry or software errors. Data Quality and Coverage : Table 1 contains hourly summaries of the percentage of the data available, data quality, and contamination codes. Tables 2 and 3 contain descriptions of the data quality and data contamination ID's respectively. ------------------------------------------------------------------- Table 1. Hourly Data Coverage and Quality Summaries ------------------------------------------------------------------- Start Time Mode Percent Qual Contam NumGood ------------------------------------------------------------------- 1989-08-24T19:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-24T20:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-24T21:00:00 ENCOUNTER 95.667 -1 -1 1435 1989-08-24T22:00:00 ENCOUNTER 97.333 -1 -1 1460 1989-08-24T23:00:00 ENCOUNTER 94.333 -1 -1 1415 1989-08-25T00:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T01:00:00 ENCOUNTER 93.667 -1 -1 1405 1989-08-25T02:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T03:00:00 ENCOUNTER 84.667 -1 -1 1270 1989-08-25T04:00:00 ENCOUNTER 96.667 -1 -1 1450 1989-08-25T05:00:00 ENCOUNTER 94.667 -1 -1 1420 1989-08-25T06:00:00 ENCOUNTER 99.000 -1 -1 1485 1989-08-25T07:00:00 ENCOUNTER 98.333 -1 -1 1475 1989-08-25T08:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T09:00:00 ENCOUNTER 98.667 -1 -1 1480 1989-08-25T10:00:12 ENCOUNTER 99.667 -1 -1 1495 1989-08-25T11:00:00 ENCOUNTER 94.667 -1 -1 1420 1989-08-25T12:00:00 ENCOUNTER 98.000 -1 -1 1470 1989-08-25T13:00:00 ENCOUNTER 97.667 -1 -1 1465 1989-08-25T14:00:00 ENCOUNTER 98.667 -1 -1 1480 1989-08-25T15:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T16:00:00 ENCOUNTER 98.000 -1 -1 1470 1989-08-25T17:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T18:00:00 ENCOUNTER 98.000 -1 -1 1470 1989-08-25T19:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T20:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T21:00:00 ENCOUNTER 98.333 -1 -1 1475 1989-08-25T22:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-25T23:00:00 ENCOUNTER 96.000 -1 -1 1440 1989-08-26T00:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T01:00:00 ENCOUNTER 98.333 -1 -1 1475 1989-08-26T02:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T03:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T04:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T05:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T06:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T07:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T08:00:00 ENCOUNTER 100.000 -1 -1 1500 1989-08-26T08:19:48 ENCOUNTER 33.333 -1 -1 500 -------------------------------------------------------------------- Table 2. Data Quality ID Descriptions -------------------------------------------------------------------- ID Description -------------------------------------------------------------------- -1 no attempt has been made to specify a data quality for this time range -------------------------------------------------------------------- Table 3. Data Contamination ID Descriptions -------------------------------------------------------------------- ID Description -------------------------------------------------------------------- -1 no evaluation of possible contamination has been made