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NASA Space Science Data Coordinated Archive Header



Availability: Archived at NSSDC, accessible from elsewhere

Time span: 1989-08-24 to 1989-08-26


This description was generated automatically using input from the Planetary Data System.

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.

These data are available on-line from the Planetary Data System (PDS) at:

Alternate Names



  • Planetary Science: Fields and Particles

Additional Information


Questions and comments about this data collection can be directed to: Dr. Edwin V. Bell, II



NameRoleOriginal AffiliationE-mail
Dr. John E. P. ConnerneyGeneral ContactNASA Goddard Space Flight
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