KPL/PCK Enceladus (PcK) SPICE kernel file =========================================================================== Overview -------------------------------------------------------- This PCK provides Enceladus rotation constants determined in 2023 by the Solar System Dynamics (SSD) team, JPL in the process of deriving their SPC-based Enceladus shape model. In this file, the Saturnian system and Enceladus nutation precession angles constants derived by SSD were updated to allow loading this PCK *after* either pck00010.tpc or pck00011.tpc so that data from both kernels can be used together. Given this load order, orientation and radius data for Enceladus will match those derived by SSD, while data for all other objects, including the other objects in the Saturnian system, will match those from pck00010.tpc or pck00011.tpc. It is not possible to use these kernels in combination to provide data for objects of the Saturnian system if this PCK is loaded *before* pck00010.tpc or pck00011.tpc. To safely use pck00010.tpc or pck00011.tpc after this PCK has been loaded, this PCK must be unloaded first. 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 ``Version Description'' section if you modify the file. Version Description -------------------------------------------------------- Version 1.0 -- November 5, 2023 -- Ryan Park, Nat Bachman, and Boris Semenov Contact Information -------------------------------------------------------- Ryan Park, ryan.s.park@jpl.nasa.gov References -------------------------------------------------------- Park et al., The global shape, gravity field, and libration of Enceladus, submitted. Jacobson, R. A., Brozovic, M., Mastrodemos, N., Riedel, J. E., & Sheppard, S. S. (2022). Ephemerides of the Irregular Saturnian Satellites from Earth-based Astrometry and Cassini Imaging. Astronomical Journal, 164(6). Constants for Saturn System -------------------------------------------------------- Saturn nutation/precession angles. This PCK contains Saturnian system nutation precession angle data both derived by SSD and from pck00010.tpc or pck00011.tpc (which have the same values). The first 16 values are from pck00011.tpc. The remaining 36 values are from the SSD model. Note that the optional commas from the initial SSD PCK have been retained for convenient comparison. These have no effect on data read and stored by SPICE software. \begindata BODY6_NUT_PREC_ANGLES = ( 353.32 75706.7 28.72 75706.7 177.40 -36505.5 300.00 -7225.9 316.45 506.2 345.20 -1016.3 706.64 151413.4 57.44 151413.4 335.844470, 51.7682239, 355.351814, 101.6467750, 9.369346, 1004.8728024, 129.755966, 1223.2050690, 219.755966, 1223.2050690, 159.835559, 2445.2902118, 249.835559, 2445.2902118, 117.392885, 3667.0200695, 280.169482, 7226.3782354, 6.997174, 36506.5422127, 196.673251, 15227.2035409, 253.848856, 3258.6617087, 136.859155, 9266.8742489, 144.630256, 12292.3910895, 9.821866, 16090.5831593, 226.334387, 17383.5986496, 93.360491, 18531.0794323, 10.9818392, 9583937.8056363 ) \begintext Orientation constants for Enceladus -------------------------------------------------------- The inertial reference frame for Enceladus constants is ICRF; 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 Enceladus is 602. See the NAIF_IDs required reading for further information on NAIF integer codes. These rotation constants were used to produce and are consistent with the Enceladus DSKs produced by the SSD team in 2023. The nutation precession angle coefficients for Enceladus are compatible with the Saturnian system nutation precession angles provided above. Data taken from SSD-derived model have not been modified; the contents of the kernel variables containing the data have been structured to enable use of this PCK and PCKs pck00010.tpc or pck00011.tpc together. \begindata BODY602_POLE_RA = ( 40.592915, -0.0902111773, 0.0 ) BODY602_POLE_DEC = ( 83.534180, -0.0071054901, 0.0 ) BODY602_PM = ( 7.120600, 262.7318870466, 0.0 ) BODY602_NUT_PREC_RA = ( 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.026616, 0.000686, -0.000472, -0.000897, 0.002970, 0.001127, 0.000519, 0.000228, 0.036804, -0.001107, 0.073107, -0.000167, 0.000000, 0.000000, -0.000376, 0.000248, -0.000137, 0.000000 ) BODY602_NUT_PREC_DEC = ( 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.004398, -0.000264, -0.000185, -0.000093, -0.000068, -0.000236, 0.000000, -0.000028, 0.004141, -0.000124, 0.008229, 0.000007, 0.000000, 0.000000, -0.000039, 0.000026, -0.000016, 0.000000 ) BODY602_NUT_PREC_PM = ( 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.026447, -0.000682, 0.000469, -0.005118, 0.036955, -0.013111, 0.014206, -0.006687, -0.036404, 0.001082, -0.072604, -0.266358, -0.188429, -0.004710, 0.000337, -0.000183, -0.001724, -0.091295 ) \begintext Radii for asteroid Enceladus -------------------------------------------------------- These Enceladus radii are consistent with the Enceladus DSKs produced by the SSD team in 2023. \begindata BODY602_RADII = ( 256.14 251.16 248.68 ) \begintext End of PCK file.