KPL/PCK

Asteroid Psyche P_constants (PcK) SPICE kernel file
===========================================================================
 
   This text PCK contains rotational and ellipsoidal shape constants
   for asteroid Psyche, as well as a definition of frame PSYCHE_FIXED. 

 
Version and Date
--------------------------------------------------------
 
   Version 0.1 -- January 18, 2023 -- Matt Barnes, NAIF/JPL
                                      Gregory Lantoine, JPL

      Updated rotation constants and radii per [3].

   Version 0.0 -- April 10, 2018 -- Ryan Park, JPL

      Preliminary PCK containing draft values for the pole
      direction, prime meridian location, rotation period and 
      shape (from [1].) 
 

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 and Date'' section if 
   you modify the file.


Sources
--------------------------------------------------------

   The sources for the constants listed in this file are:

      1) Shepard, Michael K., et al. ``Radar observations and shape
         model of asteroid 16 Psyche'' ICARUS 281, 2017.
         http://dx.doi.org/10.1016/j.icarus.2016.08.011

         The Psyche coordinate system is shown in the ecliptic frame
         (EMO2000) in Shepard et al. (2017), which was rotated into
         the equatorial frame (EME2000) and truncated at the 0th
         decimal place since the uncertainty is > 1 deg.

         The prime meridian value (W0) is what was used to fit the
         radar shape in Shepard et al. (2017) and the value was
         provided via email.

      2) Baer, James and Chesley, Steve R., ``Simultaneous Mass
         Determination for Gravitationally Coupled Asteroids'' ASTRON.
         J. 154, 2017. https://doi.org/10.3847/1538-3881/aa7de8

      3) Psyche Project ``Planetary Constants and Models Document'',
         Revision C.

      4) Shepard, Michael K., et al. ``Asteroid 16 Psyche: Shape, 
         Features, and Global Map'', The Planetary Science Journal, 
         Volume 2, Number 4, July 2021
         https://doi.org/10.3847/PSJ/abfdba


Orientation constants for asteroid Psyche
--------------------------------------------------------

Values in Version 0.0 

   The rotation constants below are from [1]. 

   The values are saved in comments for traceability, lower-cased to 
   prevent accidental use.

      body2000016_pole_ra    = (  34.00    0.0       0.0 )
      body2000016_pole_dec   = (   6.00    0.0       0.0 )
      body2000016_pm         = ( 266.75  2059.12942677   0.0 )

Values in Version 0.1 

   The rotation constants below are from [3]. 

   Note that the values presented here, taken from [3], are based
   of the original values from [4] rotated from the ecliptic frame
   to the J2000 frame and rounded to the nearest integer due to
   the magnitude of their uncertainties.

   \begindata
 
      BODY2000016_POLE_RA    = (  36.0      0.0          0.0 )
      BODY2000016_POLE_DEC   = (   6.0      0.0          0.0 )
      BODY2000016_PM         = ( 266.75  2059.12942677   0.0 )

   \begintext


Radii for asteroid Psyche
--------------------------------------------------------
     
Values in Version 0.0 

   The radii values below are from [1]. 

   The values are saved in comments for traceability, lower-cased to 
   prevent accidental use.

      body2000016_radii      = ( 139.5  116.0  94.5 )
 
Values in Version 0.1

   The radii values below are from [3].

   \begindata
 
      BODY2000016_RADII      = ( 139.0  119.0  85.5 )
 
   \begintext


GM for asteroid Psyche
--------------------------------------------------------

   The GM value below is from [2].

   \begindata

      BODY2000016_GM         = (  1.53  )
 
   \begintext


PSYCHE_FIXED Frame Definition
--------------------------------------------------------

   The primary location of this frame definition is in the Psyche
   mission FK file. It is included in this PCK solely for
   convenience.

   The Psyche fixed frame is defined in the same as any other PCK
   frame:

      *  +Z along the North pole;

      *  +X toward the prime meridian;

      *  +Y completes the right hand frame;

      *  the origin of this frame is at the center of the body.

   The orientation of this frame is computed by evaluating
   corresponding rotation constants provided in this PCK file.

   \begindata

      FRAME_PSYCHE_FIXED               =  2000016
      FRAME_2000016_NAME               = 'PSYCHE_FIXED'
      FRAME_2000016_CLASS              =  2
      FRAME_2000016_CLASS_ID           =  2000016
      FRAME_2000016_CENTER             =  2000016
      OBJECT_2000016_FRAME             = 'PSYCHE_FIXED'

   \begintext

End of PCK file.