KPL/PCK

\beginlabel
PDS_VERSION_ID               = PDS3
RECORD_TYPE                  = STREAM
RECORD_BYTES                 = "N/A"
^SPICE_KERNEL                = "dawn_ceres_v05.tpc"
MISSION_NAME                 = "DAWN MISSION TO VESTA AND CERES"
SPACECRAFT_NAME              = DAWN
DATA_SET_ID                  = "DAWN-M/A-SPICE-6-V1.0"
KERNEL_TYPE_ID               = PCK
PRODUCT_ID                   = "dawn_ceres_v05.tpc"
PRODUCT_CREATION_TIME        = 2015-10-19T11:30:28
PRODUCER_ID                  = "NAIF/JPL"
MISSION_PHASE_NAME           = {
                               "INITIAL CHECKOUT (ICO)",
                               "EARTH-MARS CRUISE (EMC)",
                               "MARS GRAVITY ASSIST (MGA)",
                               "MARS-VESTA CRUISE (MVC)",
                               "VESTA ENCOUNTER",
                               "VESTA-CERES CRUISE (VCC)",
                               "CERES ENCOUNTER",
                               "END OF MISSION"
                               }
PRODUCT_VERSION_TYPE         = ACTUAL
PLATFORM_OR_MOUNTING_NAME    = "N/A"
START_TIME                   = "N/A"
STOP_TIME                    = "N/A"
SPACECRAFT_CLOCK_START_COUNT = "N/A"
SPACECRAFT_CLOCK_STOP_COUNT  = "N/A"
TARGET_NAME                  = "1 CERES"
INSTRUMENT_NAME              = "N/A"
NAIF_INSTRUMENT_ID           = "N/A"
SOURCE_PRODUCT_ID            = "N/A"
NOTE                         = "See comments in the file for details"
OBJECT                       = SPICE_KERNEL
  INTERCHANGE_FORMAT         = ASCII
  KERNEL_TYPE                = TARGET_CONSTANTS
  DESCRIPTION                = "SPICE PCK file containing constants for
Ceres, created by NAIF, JPL. This PCK incorporates shape and rotation
constants from the ``Ceres Coordinate System Description'' document dated
14-Oct-2015. "
END_OBJECT                   = SPICE_KERNEL
\endlabel


Asteroid Ceres P_constants (PcK) SPICE kernel file
===========================================================================
 
 
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

         --   GM for asteroid Ceres


Version Description
--------------------------------------------------------
 

     Version 0.5 -- October 16, 2015  -- Carol Raymond, DAWN; Boris Semenov,
                                      NAIF

        Ceres rotation constants and radii were updated based on [6];
        Ceres GM was updated based on [7]. A typo in the shape section
        comments for versions 0.3 and 0.4 was fixed ("as a sphere with a
        radius of 480 km" -> "as a sphere with a radius of 470 km")

     Version 0.4 -- July 15, 2015  -- Don Han, DAWN NAV; Boris Semenov,
                                      NAIF

        Fixed typo in Ceres rotation rate in BODY2000001_PM: 951.1532 ->
        952.1532.

     Version 0.3 -- June 11, 2015  -- Don Han, DAWN NAV; Boris Semenov,
                                      NAIF

        Ceres rotation constants and radii were updated based on [5].

     Version 0.2 -- March 2, 2015  -- Don Han, DAWN NAV; Boris Semenov,
                                      NAIF

        Ceres rotation constants were updated based on [4]; Keyword for
        Ceres GM was added to the file and set to the value from [4].

     Version 0.1 -- February 25, 2011 -- Boris Semenov, NAIF

        Ceres pole orientation constants and radii were set to the
        values from [3].

     Version 0.0 -- October 12, 2004 -- Boris Semenov, NAIF
     
        Initial 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 ``Version Description'' section
     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

        4) "DAWN Planetary Constants and Models Document", Revision 4.0, 
           Mar 2, 2015

        5) "DAWN Planetary Constants and Models Document", Revision 5.0, 
           Jun 10, 2015

        6) "Ceres Coordinate System Description", C. Raymond, JPL and
           T. Roatsch, DLR, 14-OCT-2015, in PDS peer-review, to be
           archived.

        7) "Physical Properties of Ceres from the Dawn Mission", R. Park, 
           et al., Geophys. Res. Let., to be submitted, Oct. 2015


Orientation constants for asteroid Ceres
--------------------------------------------------------
 
     The inertial reference frame for Ceres 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.


Values in the Version 0.0
 
     The PCK 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 corresponding keywords were set as follows:

        body2000001_pole_ra    = ( 300.4       0.0       0.0 )
        body2000001_pole_dec   = (  53.1       0.0       0.0 )
        body2000001_pm         = (   0.0     952.0661157 0.0 )


Values in the Version 0.1

     In the PCK version 0.1 the pole direction, prime meridian
     location, and rotation period were 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
        ...

        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 corresponding keywords were set as follows:

        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 )


Values in the Version 0.2

     In the PCK version 0.2 the pole direction, prime meridian
     location, and rotation period were set to the following values from
     [4]:

        6.3 Ceres Pole and Prime Meridian

        The Ceres pole and prime meridian values are shown below.

        RA  Ceres   291.82 deg           Right Ascension in EME2000 [29]
        DEC Ceres    66.88 deg           Declination in EME2000 [29]
        W   Ceres   353.7987 + w * D deg Prime Meridian [*]
        w   Ceres   952.055 deg/day      Rotation rate [29]

        [*] This document overlooked the Ceres prime meridian and
        rotation rate recommended by Archinal et. al. [28] in IAU
        working group report and listed the prime meridian with zero
        offset until revision 4 date. While updating the prime meridian
        definition, Dawn project decided to update other physical
        parameters of Ceres by navigation team~s latest estimation
        result. The rotation rate is from navigation team report [29]
        and the prime meridian offset was calculated to match the value
        from IAU recommendation [28] at the time of RC2 (2015/02/20
        12:00:00 UTC).

        ...

        9 References

        29. "Ceres Parameters from OD", Brian Kennedy, JPL internal 
            E-mail, Feb. 26, 2015

     The corresponding keywords were set as follows:

        body2000001_pole_ra    = ( 291.82      0.0       0.0 )
        body2000001_pole_dec   = (  66.88      0.0       0.0 )
        body2000001_pm         = ( 353.7987  952.055     0.0 )


Values in the Versions 0.3 and 0.4

     In the PCK versions 0.3 and 0.4 the pole direction, prime meridian
     location, and rotation period were set to the following values from
     [5]:

        6.3 Ceres Pole and Prime Meridian

        The Ceres pole and prime meridian values are shown below.

        RA  Ceres   291.41 deg           Right Ascension in EME2000 [31] 
        DEC Ceres    66.79 deg           Declination in EME2000 [31] 
        W   Ceres   170.9 + w * D deg    Prime Meridian [30] 
        w   Ceres   952.1532 deg/day     Rotation rate [30] 

        ...

        9 References

        30. "Ceres lightcurve analysis ~ Period determination", 
            M. A. Chamberlain, et al., Icarus 188, 2007

        31. "Shape model and rotational state of dwarf planet Ceres 
            from Dawn-FC RC3 stereo images", Frank Preusker, Dawn 
            internal presentation, May 26, 2015 

     The corresponding keywords were set as follows:
 
        body2000001_pole_ra    = ( 291.41     0.0          0.0 )
        body2000001_pole_dec   = (  66.79     0.0          0.0 )
        body2000001_pm         = ( 170.9    952.1532       0.0 )



Values in the Current Version 0.5

     In the current PCK version 0.5 the pole direction, prime meridian
     location, and rotation period are set to the values obtained from
     the Dawn Approach, RC3 and Survey mission phases, as summarized in
     [6]:

        ...

        Table 1: Comparison of pre-Dawn and post-Survey Dawn coordinate
        systems; row 2 -- "Dawn Update":

        RA  Ceres   291.418 deg           Right Ascension in EME2000
        DEC Ceres    66.764 deg           Declination in EME2000
        W   Ceres   170.650 + w * D deg   Prime Meridian
        w   Ceres   952.1532 deg/day      Rotation rate

        ...

        References:
 
        "Shape model and rotational state of dwarf planet Ceres from 
        Dawn FC stereo images", Frank Preusker, et al., Euro. Plan. 
        Sci. Congress, Oct. 2015   
        ..."

     \begindata
 
        BODY2000001_POLE_RA    = ( 291.418     0.0          0.0 )
        BODY2000001_POLE_DEC   = (  66.764     0.0          0.0 )
        BODY2000001_PM         = ( 170.65    952.1532       0.0 )

     \begintext


Radii for asteroid Ceres
--------------------------------------------------------
     

Values in the Version 0.0

     In the PCK version 0.0 the radii were set to the following values
     from [2]:

        body2000001_radii      = ( 475.0     475.0     475.0 )


Values in the Versions 0.1 and 0.2

     In the versions 0.1 and 0.2 the radii were set to the following
     values from [3]/[4]:

        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

        ...
        18. "Differentiation of the asteroid Ceres as revealed by its 
            shape", P. C. Thomas, et al, Nature, 437, 224, 2005.
        ..."

     The corresponding keyword was set as follows:

        body2000001_radii      = ( 487.3     487.3     454.7 )


Values in the Versions 0.3 and 0.4

     In the PCK versions 0.3 and 0.4 the radii were set to the following
     values from [5]:

        6.4 Ceres Shape Parameters

        The Ceres shape is described by triaxial ellipsoid with values
        482.64 km, 480.60 km, 445.57 km [31] or as a sphere with a
        radius of 470 km. ...

        9 References

        ...
        31. "Shape model and rotational state of dwarf planet Ceres 
            from Dawn-FC RC3 stereo images", Frank Preusker, Dawn 
            internal presentation, May 26, 2015 
        ..."

     The corresponding keyword was set as follows:
 
        body2000001_radii      = ( 482.64  480.60  445.57 )


Values in the Current Version 0.5

     In the current PCK version 0.5 the radii are set to the spheroid
     values from [6]:

        Table 1: Comparison of pre-Dawn and post-Survey Dawn coordinate
        systems; row 2 -- "Dawn Update":

        Sphere:

           Rsp = 470 km       Equivalent spherical body radius

        Spheroid:

           Re  = 482 km       Average equatorial radius of the oblate spheroid
           Rp  = 446 km       Polar radius

        References:
 
        "Shape model and rotational state of dwarf planet Ceres from 
        Dawn FC stereo images", Frank Preusker, et al., Euro. Plan. 
        Sci. Congress, Oct. 2015   
        ..."

     \begindata
 
        BODY2000001_RADII      = ( 482     482     446    )
 
     \begintext


GM for asteroid Ceres
--------------------------------------------------------


Value in the Versions 0.0 and 0.1

      No Ceres GM was provided in the PCK version 0.0 and 0.1.


Value in the Versions 0.2, 0.3, and 0.4

     In the PCK versions 0.2, 0.3, and 0.4 the Ceres GM was set to the
     following value from [4]:

        6.2 Ceres Gravity Model

        GM Ceres = 62.68 km3/s2 Gravitational Parameter [29]

        ...

        9 References

        29. "Ceres Parameters from OD", Brian Kennedy, JPL internal 
            E-mail, Feb. 26, 2015

     The corresponding keyword was set as follows:

        body2000001_gm         = (  62.68  )


Value in the Current Version 0.5

     In the PCK version 0.5 the Ceres GM is set to the following value 
     from [7]:

        GM Ceres = 62.6325 km3/s2

     \begindata

        BODY2000001_GM         = ( 62.6325 )
 
     \begintext


End of PCK file.
