KPL/PCK Asteroid Ceres P_constants (PcK) SPICE kernel file =========================================================================== By: Boris Semenov (NAIF) 25-FEB-2011 Organization -------------------------------------------------------- The sections of this file are as follows. Introductory Information: -- Version description -- Disclaimer -- Sources Pck Data: -- Orientation constants for asteroid Ceres -- Radii for asteroid Ceres Version description -------------------------------------------------------- This file was updated on February 25, 2011. Ceres pole orientation constants and radii were to the values from "Dawn Planetary Constants and Models Document" Revision 2.0, Feb 16, 2011 This file was created on October 12, 2004. This is a preliminary PCK containing draft values for the pole direction, rotation period and shape (from [1] and [2]) and placeholder value for prime meridian. Disclaimer -------------------------------------------------------- This constants file may not contain the parameter values that you prefer. Note that this file may be readily modified by you or anyone else. NAIF suggests that you inspect this file visually before proceeding with any critical or extended data processing. NAIF requests that you update the ``by line'' and date if you modify the file. Sources -------------------------------------------------------- The sources for the constants listed in this and the earlier versions of this file are: 1) Saint-Pe, O., M. Combes, F. Rigaut (1993). Ceres surface properties by high-resolution imaging from Earth. Icarus 105, 271-281. 2) JPL Solar System Dynamic Group Horizon's System. 3) "Dawn Planetary Constants and Models Document" Revision 2.0, Feb 16, 2011 Orientation constants for asteroid Ceres -------------------------------------------------------- The inertial reference frame for these constants is J2000; this is the default reference frame for PCK orientation data. The epoch of the constants is J2000; this is Julian ephemeris date (JED) 2451545.0. The NAIF integer code for Ceres is 2000001. See the NAIF_IDs required reading for further information on NAIF integer codes. The previous version of this file (version 0.0) provided the pole direction RA = 300.4 deg and DEC = 53.1 deg (derived from the ecliptic equinox B1950.0 latitude = 70 deg and longitude = 332 deg values given in [1]), the W1 term = 952.06611570 deg/day (derived from the rotation period of 9.075 hours provided in [2]), and the W0 term arbitrarily set to 0. The pole direction, prime meridian location, rotation period and radii in this version are set to the following values from [3]: "6.3 Ceres Pole and Prime Meridian The Ceres pole and prime meridian values are shown below. RA Ceres 291 deg Right Ascension in EME2000 [17] DEC Ceres 59 deg Declination in EME2000 W Ceres 0 + w * D deg Prime Meridian w Ceres 951.5418502 deg/day Rotation rate ... 6.4 Ceres Shape Parameters The Ceres shape is described by an oblate spheroid with values 487.3 km and 454.7 km [18] or as a sphere with a radius of 480 km. ... 9 References ... 17. "Ceres: High-resolution imaging with HGA and the determination of physical properties," J. W. Parker et al., Advances in Space Research 38 (2006) 2039-2042. 18. "Differentiation of the asteroid Ceres as revealed by its shape", P. C. Thomas, et al, Nature, 437, 224, 2005. ..." The Ceres orientation constants are provided in the keywords below. \begindata BODY2000001_POLE_RA = ( 291.0 0.0 0.0 ) BODY2000001_POLE_DEC = ( 59.0 0.0 0.0 ) BODY2000001_PM = ( 0.0 951.5418502 0.0 ) \begintext Radii for asteroid Ceres -------------------------------------------------------- The Ceres radii from [3] are provided in the keyword below. \begindata BODY2000001_RADII = ( 487.3 487.3 454.7 ) \begintext End of PCK file.