# Presentation: 313813

##    CARTOGRAPHIC COORDINATES & ROTATIONAL ELEMENTS OF PLANETS & SATELLITES P.K. SeidelmannUniversity of Virginia 

## Merton Davies

**  ****Established IAU/IAG Working Group on Cartographic Coordinates.**
**  ****Was Working Group Chairman 1976-1997**
**  ****Drafted WG Reports for 1979, 1982, 1985, 1988, 1991, 1994**
**  ****Was a member of many NASA planetary missions teams**
**  ****Established Coordinate Systems for many planets & satellites**** **

## IAU/IAG/COSPAR Working Groups Reports In

**“****Celestial Mechanics & Dynamical Astronomy”**
**	****1980:  Volume 22, 205-230**
**	****1983:****	****	**** 29, 309-321**
**	****1986:****	****	**** 39, 103-113**
**	****1989:****	****	**** 46, 187-204**
**	****1992:****	****	**** 53, 377-397**
**	****1996:****	****	**** 63, 127-148**
**	****2002:****	****	**** 82, 83-110**

**IAU Transactions**
**17 B, 72-79**
**18 B, 151-162**

## Working Group Membership

**V.K. Abalakin****	****Russia****	****1976-2000**
**M. A'Hearn****	****USA            ****	****2001-2003**
**B. Archinal ****	****USA             2001-2003**
**A. Brahic****	****	****France       ****	****1988-1991**
**M. Bursa****	****	****Czech Rep  ****	****1982-2000**
**B.H. Chovitz****	****USA            ****	****1988-1991**
**C.A. Cross****	****	****England      ****	****1976-1979**
**D. Cruikshank****	****USA            ****	****2001-2003**
**M.E. Davies****	****USA            ****	****1976-2001**
**R.L. Duncombe****	****USA            ****	****1976-1979**
**C. DeBergh****	****	****France        ****	****1997-2000**
**G.E. Hunt****	****	****England      ****	****1985-1988**
**H.U. Keiller****	****Germany    ****	****2001-2003**
**H. Kinoshita****	****Japan         ****	****1994-1997**
**T. Lederle****	****	****Germany    ****	****1982-1985**
**J.H. Lieske****	****	****USA           ****	****1979-2003**
**M. Marov****	****	****Russia         ****	****1994-1997**
**H. Masursky****	****USA            ****	****1976-1979**
**   **

**B. Morando****	****France****	****1976-9,85-8,92-4**
**D. Morrison     ****	****USA            1992-1994**
**J. Oberst       ****	****Germany    1997-2003**
**T.C. Owen       ****	****USA            1976-1979**
**R.H. Rapp       ****	****USA            1982-1988**
**P.K. Seidelmann****	****USA            1976-2003**
**J.L. Simon      ****	****France        1997-2003**
**A.T. Sinclair   ****	****England      1976-1997**
**A.M. Sinzi      ****	****Japan          1979-1982**
**B.A. Smith      ****	****USA            1979-1982**
**E.M. Standish   ****	****USA            1997-2000**
**P. Stooke       ****	****Canada       1997-2003**
**V.G. Teifel     ****	****USSR          1982-1985**
**D. Tholen       ****	****USA            2001-2003**
**P.C. Thomas     ****	****USA            1997-2003**
**Y.S. Tjuflin    ****	****USSR          1976-1995**
**G.A. Wilkins    ****	****England      1976-1979**
**B. Yallop       ****	****England      1992-1995**
** **

## Guiding Principles

**Adopted by the IAU in 1970.**
** **
**1. Rotational Pole on the north side of invariable plane is north pole, northern latitudes are designated as positive.**
** **
**2. Planetographic longitude of central meridian, as observed from a direction fixed with respect to an inertial coordinate system, shall increase with time from 0 to 360 degrees. ( Exceptions are the Earth and Moon where longitudes are measured 0 to 180 degrees east and west.)**

## Definitions of Rotational Elements

** ****North pole is given by its right ascension and declination.**
** ****Variable quantities are given in units of days or Julian centuries from epoch J2000.0, or JD 2451545.5 TDB. ( Needs to be changed to TCB.)**
** ****Prime Meridian is specified by the angle W measured along the body's equator in easternly direction on the body's surface from the ascending node of the body's equator on the standard equator to the point where the prime meridian crosses the body's equator.**
** ****Prime meridian is identified by observable surface feature if possible. When there are no observable surface features, the W expression defines the prime meridian.**
** ****W is defined by plane containing centers of satellite, planet, and Sun at superior heliocentric conjunction of satellite and planet after standard epoch.**

## Cartographic Coordinate System

** ****PLANETOCENTRIC**
**      ****Used for general purposes**
**      ****Based on right-handed system of axes**
**      ****latitude is the angle between equatorial plane and line from center of mass to point**
**      ****longitudes measured positively to the east**
**      ****longitude measured from ephemeris position of prime meridian**
**      ****radius measured from center of mass**
** **
** ****PLANETOGRAPHIC**
**      ****Used for cartographic purposes**
**      ****Depend on adopted parameters to define reference system**
**      ****latitude is angle between equatorial plane and normal to reference surface at the point**
**      ****longitudes measured in direction opposite to rotation, i.e. positively to the west for direct rotation**
**      ****longitude measured from observable feature, if possible**
**      ****point, not on surface, specified by height above surface point on normal from non-surface point**
** **
** ****Both cases**
**      ****z-axis is mean axis of rotation**
**      ****planetary equator is normal to axis and through center of mass**
**      ****x-axis is intersection of planes of equator and prime meridian**
**      ****latitude measured north and south of equator**
**      ****longitude measured around equatorial plane from prime meridian from 0-360 degrees**

## Observations and Standard Values

-  **Space missions and observations    ****	****	****Coordinate systems for bodies**
**      ****	****radar measures                      ****	****Venus**
**                                          ****	****	****	****Mars**
**                                         ****	****	****	****asteroids**
**      ****	****lunar ranging                       ****	****	****Moon**
**      ****	****Apollo                              ****	****	****Moon**
**      ****	****Mariner 10                          ****	****	****Mercury**
**      ****	****Mariner 5                           ****	****	****Venus**
**      ****	****Magellan                            ****	****	****Venus**
**      ****	****Voyager                             ****	****	****Jupiter & its satellites**
**                                          ****	****	****	****Saturn & its satellites**
**                                          ****	****	****	****Uranus & its satellites**
**                                          ****	****	****	****Neptune & its satellites**
**      ****	****Viking                              ****	****	****Mars**
**      ****	****Mariner 9                           ****	****	****Mars & its satellites**
**      ****	****Pioneer 10 & 11                     ****	****Jupiter spin axis**
**      ****	****Galileo                             ****	****	****Jupiter & its satellites**
**                                          ****	****	****	****Asteroids**** **

## Data Tabulated

** ****Locations and motions of poles**
** ****Rotation of a prime meridian**
** ****Size and shape parameters**

## Asteroids and Comets

** ****What is needed?**
**What should be included?**
**Currently only radar and space mission observations used.**
** **
**Photometric measures are not included.**

## Future of Working Group

**New Missions**
** ****Cassini**
** ****Mars Missions**
** ****Pluto Express**
** ****Asteroid Explorations**
**IMPROVED VALUES FROM OBSERVATIONS**