**NSSDCA ID:** PSFP-00563

**Availability:** Archived at NSSDC, accessible from elsewhere

**Time span:** 1981-08-24 to 1981-09-02

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

Data Set Overview ================= This data set consists of Voyager 2 Saturn encounter ephemeris data in Heliographic coordinates covering the period 1981-08-24 to 1981-09-02. Two versions, both covering the same time period, but containing slightly different data, are provided. One version was generated by the Voyager MAG team from Voyager 2 SEDR, the other by the PDS/PPI node using the VG2_SAT.TSP and PCK00006.TPC SPICE kernels. Due to inaccuracies in Voyager SEDR, as well as changes in the values of some key parameters (e.g. Saturn radius) the timing is improved for the SPICE generated data. However, since much of the original analysis was based upon the SEDR generated ephemeris, this data has been included as well. SEDR generated ephemeris -----------------------Data Supplier : NSSDC Data sampling rate : 96 seconds Data Set Start Time : 1981-08-24T00:00:47.596Z Data Set Stop Time : 1981-09-02T23:58:22.732Z SPICE generated ephemeris ------------------------Data Supplier : S. Joy Data sampling rate : 96 seconds Data Set Start Time : 1981-08-24T00:00:47.596Z Data Set Stop Time : 1981-09-02T23:58:22.732Z Parameters ========== SEDR generated ephemeris -----------------------PARAMETER RESOLUTION/ DESCRIPTION NAME UNITS time 96.0 Sec. time of the sample (UT) in the format yyyy-mm-ddThh:mm:ss.sssZ m65536 counts spacecraft clock counts mod60 fds_line sc_x AU heliographic cartesian coordinates sc_y position vectors: X, Y, and Z sc_z vel_x km/s heliocentric X, Y, and Z spacecraft vel_y velocity components vel_z sc_r AU heliographic spherical coordinates sc_lat degrees position vectors: range, latitude, and sc_lon degrees longitude SolEquatorial_to_HG solar equatorial to heliographic coordinates rotation matrix containing 9 1pe15.8 elements HG_to_EarthOrbTrue heliographic to earth orbit true coordinates rotation matrix containing 9 1pe15.8 elements Spacecraft_to_HG payload (spacecraft) to heliographic coordinates rotation matrix containing 9 1pe15.8 elements SPICE generated ephemeris ------------------------PARAMETER RESOLUTION/ DESCRIPTION NAME UNITS time 96.0 Sec time of the sample (UT) in the format yyyy-mm-ddThh:mm:ss.sssZ R AU heliographic spherical coordinates position vectors: range LAT degrees latitude LON degrees longitude Coordinate System ================= The Heliographic coordinate system is a heliocentric system defined in the reference epoch of 1950. The unit vectors which define the coordinate system are as follows: Heliographic cartesian coordinates X points towards the the first point of Aries in the solar equatorial plane on the vernal equinox of the reference epoch 1950 (positive away from the Sun) Y completes the right handed set (X x Z) Z points along the Sun's spin axis (positive above the equatorial plane) Heliographic spherical coordinates R (Range) the distance from the Sun's position at the reference epoch to the spacecraft in AU LAT (Latitude) the angle between the solar equatorial plane of the reference epoch measured in the plane containing the solar spin axis of that epoch (positive above the equatorial plane) LON (Longitude) longitude is zero in the direction of the ascending node at the reference epoch (X direction) and increasing in the direction of planetary orbital motion (note that LON does not rotate with the Sun) For the SPICE data, the definition used for astronomical units is 1 AU = 149674000 km. The longitude of the ascending node was calculated using the equation: LON = 74 [degrees] 22' + 0.84' * ( year - 1900 ). The inclination of the Sun's North pole measured relative to the ecliptic was defined as being 7 [degrees] 15' in 1950.

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

https://pds-ppi.igpp.ucla.edu/data/VG2-S-POS-4-SUMM-HGCOORDS-V1.0/

- VG2-S-POS-4-SUMM-HGCOORDS-V1.0

- Planetary Science: Fields and Particles

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

Name | Role | Original Affiliation | |
---|---|---|---|

Mr. Steven P. Joy | General Contact | University of California, Los Angeles | sjoy@igpp.ucla.edu |