• Data Set Overview
• =================

This Data Set consists of Voyager 2 Neptune Encounter Ephemeris Data relative to the Planet 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 h Period.

• Cartesian Coordinates

• =====================

• NLS Cartesian Coordinates

• =========================

• X lies in the Equatorial Plane of Neptune, positive away from the Planet, and through the Prime Meridian at the Reference Epoch
• Y completes the left-handed Set, Y = Z ⨯ X
• Z points along the Spin Axis of Neptune

The Prime Meridian of this System is defined such that at 1989-08-25T03:56:00.000 the Voyager 2 Spacecraft was at 167.7° West Longitude.

For the PDS Archive Data Set, the original Data Archive has been converted to an East Longitude (right-handed) Coordinate System Minus NLS (-NLS). This is achieved by reversing the Direction of the Y Axis, or in Spherical Coordinates, by subtracting the NLS Longitude from 360°. The Data are provided in Units of Neptunian Radii, which was taken to be equal to 24,765 km by the Voyager Project. Angles are given in Degrees. Both Cartesian and Spherical Coordinates are provided.

+-----------------------------------+
| Parameter Characteristics | Value |

| Processing Level ID | 4 |
| Software Flag | Y |
| Processing Start Time | UNK |
| Processing Stop Time | UNK |
+-----------------------------------+

• Parameters

• ==========

• Data Set Parameter POSITION VECTOR

• ==================================

A Position Vector is a Triad that describes the Location of a Point in three dimensional Space relative to some Origin.

+-----------------------------------------------------------------------+
| Parameter Characteristics | Value |

| Data Set Parameter Name | POSITION VECTOR |
| Data Set Parameter Unit | NEPTUNE RADII (24,765 KM) OR DEGREES |
| Sampling Parameter Name | TIME |
| Sampling Parameter Unit | SECONDS |
| Sampling Parameter Resolution | 12 |
| Sampling Parameter Interval | 12 |
| Minimum Available Sampling Int | 12 |
+-----------------------------------------------------------------------+

• Source Instrument Parameters
• ============================

N/A

• Measurement Information
• =======================

N/A

• Processing

• ==========

• Processing History

• ==================

+-------------------------------------------------------------------+
| Parameter Characteristics | Value |

| Source Data Set ID | N/A |
| Software | UNK |
| Product Data Set ID | VG2-N-POS-5-SUMM-NLSCOORDS-12SEC-V1.0 |
+-------------------------------------------------------------------+