KPL/FK Frame (FK) SPICE kernel file for Solar Orbiter-specific science frames ============================================================================== This frames kernel defines a number of generic frames used by SOLO mission for Science opportunities identification, data analysis and scientific research. These frames are currently not ``built'' into the SPICE toolkit. These frames are sorted in two groups: those that are SOLO mission specific and those that are Sun and Earth generic. The first group contains the frames defined by and for the Solar Orbiter mission, while the second provides the frames that are commonly accepted by the scientific community for the Sun. The IAU body-fixed rotational frames for the Sun is an exception to this grouping, as it is provided in a separate PCK kernel file. Version and Date ------------------------------------------------------------------------------ Version 0.2 -- March 28, 2019 -- Marc Costa Sitja, ESAC/ESA Bill Thomson, JPL/NASA Corrected SOLO_SUN_RTN frame definition and updates names and IDs for the frames from [17]. Corrected SOLO_GAE for it cannot be a rotating frame if the epoch is frozen at date J2000. Version 0.1 -- October 18, 2017 -- Marc Costa Sitja, ESAC/ESA Redefined SOLO_GAE, SOLO_GSE, SOLO_HEE to be of date J2000. Added all the frames defined in [17]. Version 0.0 -- June 20, 2017 -- Marc Costa Sitja, ESAC/ESA Initial version. References ------------------------------------------------------------------------------ 1. ``Frames Required Reading'' 2. ``Kernel Pool Required Reading'' 3. ``Report of the IAU/IAG/COSPAR Working Group on Cartographic Coordinates and Rotational Elements: 2003.'' 4. ``Report of the IAU/IAG/COSPAR Working Group on Cartographic Coordinates and Rotational Elements: 2009.'' 5. ``Dynamic Heliospheric Coordinate Frames developed for the NASA STEREO mission'', heliospheric_v004u.tf from the NEW HORIZONS NH-J/P/SS-SPICE-6-V1.0 dataset. 6. ``Solar Orbiter Science Operations Frames'', solo_ANC_soc-sci-fk_V00.tf. 7. ``List of needed frames for Solar Orbiter'', Solar Orbiter Confluence, https://issues.cosmos.esa.int/solarorbiterwiki/display/ SOL/List+of+needed+frames+for+Solar+Orbiter 8. ``Generic Frame Definitions Kernel for Heliocentric frames'', sun_v02.tf, Draft Generic Frame Kernel from NAIF. 9. http://stereo.sr.unh.edu/data/PLASTIC_Resources/ stereo_coordinates.pdf 10. Weiduo Hu, "Fundamental Spacecraft Dynamics and Control," Wiley 2015 11. Li, H., "Geostationary Satellites Collocation," Springer, 2014 12. ``The SunSPICE Ephemeris Package for Solar Missions'', Thompson, W., August 4, 2016. 13. Hapgood,M. (1992). "Space physics coordinate transformations: A user guide," Planetary and Space Science, 40, 711-717 14. OMNIWeb - Description of Heliospheric Coordinate Systems: http://omniweb.gsfc.nasa.gov/coho/helios/plan_des.html 15. Franz and Harper. (2002) "Heliospheric Coordinate Systems," Space Science, 50, 217ff. 16. Seidelmann, P.K., "Explanatory Supplement to the Astronomical Almanac," (1992), University Science Books. 17. ``Dynamic Heliospheric Coordinate Frames developed for the NASA STEREO mission'', heliospheric__v004u.tf, William Thompson, Brian T. Carcich, April 19, 2016. Contact Information ------------------------------------------------------------------------------ If you have any questions regarding this file contact SPICE support at ESAC: Marc Costa Sitja (+34) 91-8131-457 mcosta@sciops.esa.int, esa_spice@sciops.esa.int or the Solar Orbiter Science Operations Center at ESAC: sol_soc@esa.int Implementation Notes ------------------------------------------------------------------------------ This file is used by the SPICE system as follows: programs that make use of this frame kernel must "load" the kernel normally during program initialization. Loading the kernel associates the data items with their names in a data structure called the "kernel pool". The SPICELIB routine FURNSH loads a kernel into the pool as shown below: FORTRAN: (SPICELIB) CALL FURNSH ( frame_kernel_name ) C: (CSPICE) furnsh_c ( frame_kernel_name ); IDL: (ICY) cspice_furnsh, frame_kernel_name MATLAB: (MICE) cspice_furnsh ( 'frame_kernel_name' ) PYTHON: (SPICEYPY)* furnsh( frame_kernel_name ) In order for a program or routine to extract data from the pool, the SPICELIB routines GDPOOL, GIPOOL, and GCPOOL are used. See [2] for more details. This file was created and may be updated with a text editor or word processor. * SPICEPY is a non-official, community developed Python wrapper for the NAIF SPICE toolkit. Its development is managed on Github. It is available at: https://github.com/AndrewAnnex/SpiceyPy SPICE Frame names and NAIF ID Codes ------------------------------------------------------------------------------ The following generic frames are defined in this kernel file: SPICE Frame Name Long-name ------------------------- -------------------------------------------- SOLO mission specific generic frames: SOLO_SUN_RTN Sun Solar Orbiter Radial-Tangential-Normal SOLO_SOLAR_MHP S/C-centred mirror helioprojective SOLO_IAU_SUN_2009 Sun Body-Fixed based on IAU 2009 report SOLO_IAU_SUN_2003 Sun Body-Fixed based on IAU 2003 report SOLO_GAE Geocentric Aries Ecliptic at J2000 (GAE) SOLO_GSE Geocentric Solar Ecliptic at J2000 (GSE) SOLO_HEE Heliocentric Earth Ecliptic at J2000 (HEE) Heliospheric Coordinate Frames developed for the NASA STEREO mission: SOLO_ECLIPDATE Mean Ecliptic of Date Frame SOLO_GSE Geocentric Solar Ecliptic Frame SOLO_HCI Heliocentric Inertial Frame SOLO_HEE_NASA Heliocentric Earth Ecliptic Frame SOLO_HEEQ Heliocentric Earth Equatorial Frame SOLO_GEORTN Geocentric Radial Tangential Normal Frame Heliocentric Generic Frames(*): SUN_ARIES_ECL Heliocentric Aries Ecliptic (HAE) SUN_EARTH_CEQU Heliocentric Earth Equatorial (HEEQ) SUN_EARTH_ECL Heliocentric Earth Ecliptic (HEE) SUN_INERTIAL Heliocentric Inertial (HCI) Geocentric Generic Frames(*): EARTH_SUN_ECL Geocentric Solar Ecliptic (GSE) EARTH_MECL_MEQX Earth Mean Ecliptic and Equinox of date frame (Auxiliary frame for EARTH_SUN_ECL) (*) These frames are commonly used by other missions for data analysis and scientific research. In the future NAIF may include them in their official generic frames kernel for the Sun and Earth systems. When this happens the frames will be removed from this kernel. These frames have the following centers, frame class and NAIF IDs: SPICE Frame Name Center Class NAIF ID -------------------------- ---------- ------- ---------- SOLO_SUN_RTN SOLO DYNAMIC -144991 SOLO_SOLAR_MHP SOLO DYNAMIC -144992 SOLO_IAU_SUN_2009 SUN FIXED -144993 SOLO_IAU_SUN_2003 SUN FIXED -144994 SOLO_GAE EARTH DYNAMIC -144995 SOLO_GSE EARTH DYNAMIC -144996 SOLO_HEE SUN DYNAMIC -144997 SOLO_ECLIPDATE EARTH PARAM -144980 SOLO_GSE EARTH DYNAMIC -144981 SOLO_HCI SUN DYNAMIC -144982 SOLO_HEE_NASA SUN DYNAMIC -144983 SOLO_HEEQ SUN DYNAMIC -144984 SOLO_GEORTN SUN DYNAMIC -144985 SUN_ARIES_ECL SUN DYNAMIC 1000010000 SUN_EARTH_CEQU SUN DYNAMIC 1000010001 SUN_EARTH_ECL SUN DYNAMIC 1000010002 SUN_INERTIAL SUN FIXED 1000010004 EARTH_SUN_ECL EARTH DYNAMIC 300399005 EARTH_MECL_MEQX EARTH PARAM 300399000 These frames have the following common names and other designators in literature: SPICE Frame Name Common names and other designators -------------------- -------------------------------------- SUN_ARIES_ECL HAE, Solar Ecliptic (SE) SUN_EARTH_CEQU HEEQ, Stonyhurst Heliographic SUN_INERTIAL HCI, Heliographic Inertial (HGI) EARTH_SUN_ECL GSE of Date, Hapgood SUN_EARTH_ECL HEE of Date EARTH_MECL_MEQX Mean Ecliptic of Date (ECLIPDATE) The keywords implementing these frame definitions are located in the section "Generic Dynamic Frames" and "Generic Inertial Frames". General Notes About This File ------------------------------------------------------------------------------ About Required Data: -------------------- Most of the dynamic frames defined in this file require at least one of the following kernels to be loaded prior to their evaluation, normally during program initialization: - Planetary ephemeris data (SPK), e.g. DE403, DE405, etc; - Planetary constants data (PCK); - Earth generic frames definitions (FK). Note that loading different kernels will lead to different orientations of the same frame at a given epoch, providing different results from each other, in terms of state vectors referred to these frames. About Implementation: --------------------- The SPICE frames defined within this file and their corresponding references in literature might not be equivalent, both due to variations in the SPICE kernels on which the SPICE frame depends, and due to possible differences in both the frame's definition and implementation (e.g. GSE can be defined using the instantaneous orbital plane or mean ecliptic; the mean ecliptic is a function of the ecliptic model). Please refer to each applicable frame description section for particular details on the current SPICE kernel implementation. SOLO Mission Specific Scientific Frame Definitions ------------------------------------------------------------------------------ This section contains the definition of the SOLO mission specific scientific frames. Sun Solar Orbiter Radial-Tangential-Normal (SOLO_SUN_RTN) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the Sun SOLO Radial-Tangential-Normal frame is referred as SOLO_SUN_RTN. In literature, this frame is referred as RTN (from [9]), Orbit RTN Coordinate System (from [11]), or radial-transverse-normal (from [10]). Definition: ----------- The Sun SOLO Radial-Tangential-Normal frame is defined as follows (from [10]): - the position of Sun relative to SOLO is the primary vector: +X axis points from the SOLO to Sun; - the normal vector to the orbit plane defines the frame's +Z axis; - +Y axis completes the right-handed system; - the origin of this frame is the center of mass of SOLO. All vectors are geometric: no aberration corrections are used. Required Data: -------------- This frame is defined as a two-vector frame using two different types of specifications for the primary and secondary vectors. The primary vector is defined as an 'observer-target position' vector and the secondary vector is defined as an 'observer-target velocity' vector, therefore, the ephemeris data required to compute the JUICE-Sun state vector in the J2000 reference frame must be loaded before using this frame. Remarks: -------- This frame is defined based on SPK data: different planetary ephemerides for the Sun, the Solar System Barycenter and SOLO spacecraft will lead to different frame orientation at a given time. It is strongly recommended to indicate what data have been used in the evaluation of this frame when referring to it, e.g. SOLO_SUN_RTN using the DE405 ephemeris and the SOLO ephemeris version N. \begindata FRAME_SOLO_SUN_RTN = -144991 FRAME_-144991_NAME = 'SOLO_SUN_RTN' FRAME_-144991_CLASS = 5 FRAME_-144991_CLASS_ID = -144991 FRAME_-144991_CENTER = -144 FRAME_-144991_RELATIVE = 'J2000' FRAME_-144991_DEF_STYLE = 'PARAMETERIZED' FRAME_-144991_FAMILY = 'TWO-VECTOR' FRAME_-144991_PRI_AXIS = 'X' FRAME_-144991_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144991_PRI_OBSERVER = 'SOLO' FRAME_-144991_PRI_TARGET = 'SUN' FRAME_-144991_PRI_ABCORR = 'NONE' FRAME_-144991_SEC_AXIS = 'Z' FRAME_-144991_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144991_SEC_FRAME = 'IAU_SUN' FRAME_-144991_SEC_SPEC = 'RECTANGULAR' FRAME_-144991_SEC_VECTOR = ( 0, 0, 1 ) \begintext Solar Orbiter-centred mirror helioprojective (SOLO_SOLAR_MHP): ------------------------------------------------------------------------ This is a frame to be used together with Solar Orbiter FITS files. According to [7] the Solar Orbiter-centred mirror helioprojective reference frame -- SOLO_SOLAR_MHP -- is defined as follows: - +Z axis is parallel to the S/C-Sun apparent direction. - +Y axis is parallel to the Solar North, - +Y axis completes the right-handed system; - the origin of this frame is is the point of intersection of the launcher longitudinal axis with the separation plane between the launcher and the composite. The S/C-Sun vector is not geometric and aberration corrections apply to the state of the Sun to account for one-way light time and stellar aberration. This is almost the same as the SOLO_SUN_NORM frame [6], except for different axis lablelling. It is almost ``helioprojective'' except that the +X axis has been mirrored to make the system Right-Handed for SPICE. In addition the +Z axis approach is not identical (actually helioprojective is implicitly stellar aberration corrected, since it defines the apparent disk centre on the axis. Thus z-axis approach is the same). Required Data: -------------- This frame is defined as a two-vector frame using two different types of specifications for the primary and secondary vectors. The primary vector is defined as an 'observer-target position' vector. Therefore, the ephemeris data required to compute the SOLO-Sun position vector in the J2000 reference frame must be loaded before using this frame. The secondary vector is defined as a constant vector in the IAU_SUN frame, which provides the Solar North. Remarks: -------- This frame is defined based on SPK data: different planetary ephemerides for SOLO, the Sun and the Solar System Barycenter will lead to a different frame orientation at a given time. It is strongly recommended to indicate what data have been used in the evaluation of this frame when referring to it, e.g. SOLO_RARF using the IAU 2009 constants and the DE405 ephemeris. \begindata FRAME_SOLO_SOLAR_MHP = -144992 FRAME_-144992_NAME = 'SOLO_SOLAR_MHP' FRAME_-144992_CLASS = 5 FRAME_-144992_CLASS_ID = -144992 FRAME_-144992_CENTER = -144 FRAME_-144992_RELATIVE = 'J2000' FRAME_-144992_DEF_STYLE = 'PARAMETERIZED' FRAME_-144992_FAMILY = 'TWO-VECTOR' FRAME_-144992_PRI_AXIS = 'Z' FRAME_-144992_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144992_PRI_OBSERVER = 'SOLO' FRAME_-144992_PRI_TARGET = 'SUN' FRAME_-144992_PRI_ABCORR = 'LT+S' FRAME_-144992_SEC_AXIS = 'Y' FRAME_-144992_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144992_SEC_FRAME = 'IAU_SUN' FRAME_-144992_SEC_SPEC = 'RECTANGULAR' FRAME_-144992_SEC_VECTOR = ( 0, 0, 1 ) \begintext Sun Body-Fixed Frame - IAU 2009 (SOLO_IAU_SUN_2009) ------------------------------------------------------------------------ Definition: ----------- The IAU frame is defined as follows: - +Z axis is parallel to the Sun rotation axis, pointing toward the North side of the invariable plane; - +X axis is aligned with the ascending node of the Sun orbital plane with the Sun equator plane; - +Y axis completes the right-handed system; - the origin of this frame is the center of mass of the Sun. Remarks: -------- This frame is defined as a PCK-based frame, using the Sun's orientation data provided in the IAU 2009 report (see [3]). This frame is equivalent to the IAU_SUN body-fixed frame, when using pck00009.tpc and pck00010.tc. The orientation of this frame with respect to the J2000 inertial frame is provided using three Euler angles which describe the pole and prime meridian location: the first two angles, in order, are the right ascension and declination (RA and DEC) of the north pole of the Sun as a function of time. The third angle is the prime meridian location (represented by 'PM'), which is expressed as a rotation about the north pole, also a function of time. The time arguments of functions that define orientation always refer to Barycentric Dynamical Time (TDB), measured in centuries or days past J2000 epoch, which is Julian ephemeris date 2451545.0. The time units are ephemeris days for prime meridian motion and ephemeris centuries for motion of the pole. \begindata FRAME_SOLO_IAU_SUN_2009 = -144993 FRAME_-144993_NAME = 'SOLO_IAU_SUN_2009' FRAME_-144993_CLASS = 2 FRAME_-144993_CLASS_ID = -144993 FRAME_-144993_CENTER = 10 BODY-144993_POLE_RA = ( 286.13 0. 0. ) BODY-144993_POLE_DEC = ( 63.87 0. 0. ) BODY-144993_PM = ( 84.176 14.18440 0. ) BODY-144993_LONG_AXIS = ( 0. ) \begintext Sun Body-Fixed Frame - IAU 2003 (SOLO_IAU_SUN_2003) ------------------------------------------------------------------------ Definition: ----------- The IAU frame is defined as follows: - +Z axis is parallel to the Sun rotation axis, pointing toward the North side of the invariable plane; - +X axis is aligned with the ascending node of the Sun orbital plane with the Sun equator plane; - +Y axis completes the right-handed system; - the origin of this frame is the center of mass of the Sun. Remarks: -------- This frame is defined as a PCK-based frame, using the Sun's orientation data provided in the IAU 2003 report (see [4]). This frame is equivalent to the IAU_SUN body-fixed frame, when using pck00008.tpc. The orientation of this frame with respect to the J2000 inertial frame is provided using three Euler angles which describe the pole and prime meridian location: the first two angles, in order, are the right ascension and declination (RA and DEC) of the north pole of the Sun as a function of time. The third angle is the prime meridian location (represented by 'PM'), which is expressed as a rotation about the north pole, also a function of time. The time arguments of functions that define orientation always refer to Barycentric Dynamical Time (TDB), measured in centuries or days past J2000 epoch, which is Julian ephemeris date 2451545.0. The time units are ephemeris days for prime meridian motion and ephemeris centuries for motion of the pole. \begindata FRAME_SOLO_IAU_SUN_2003 = -144994 FRAME_-144994_NAME = 'SOLO_IAU_SUN_2003' FRAME_-144994_CLASS = 2 FRAME_-144994_CLASS_ID = -144994 FRAME_-144994_CENTER = 10 BODY-144994_POLE_RA = ( 286.13 0. 0. ) BODY-144994_POLE_DEC = ( 63.87 0. 0. ) BODY-144994_PM = ( 84.10 14.18440 0. ) BODY-144994_LONG_AXIS = ( 0. ) \begintext Geocentric Aries Ecliptic of J2000 frame (SOLO_GAE) ------------------------------------------------------------------------ Definition: ----------- The Heliocentric Aries Ecliptic of date frame is defined as follows (from [12]): - +Z axis is aligned with the north-pointing vector normal to the mean orbital plane of the Earth (Ecliptic North Pole); - +X axis points toward the first point of Aries, i.e. along the "mean equinox", which is defined as the intersection of the Earth's mean orbital plane with the Earth's mean equatorial plane. It is aligned with the cross product of the north-pointing vectors normal to the Earth's mean equator and mean orbit plane of date; - +Y axis is the cross product of the Z and X axes and completes the right-handed frame; - the origin of this frame is the Earth's center of mass. The mathematical model used to obtain the orientation of the Earth's mean equator and equinox of date frame is the 1976 IAU precession model, built into SPICE. The mathematical model used to obtain the mean orbital plane of the Earth is the 1980 IAU obliquity model, also built into SPICE. The base frame for the 1976 IAU precession model is J2000. Required Data: -------------- The usage of this frame does not require additional data since both the precession and the obliquity models used to define this frame are already built into SPICE. Remarks: -------- This frame is (to first order) fixed with respect to the distant stars, and therefore inertial, nevertheless it is subject to slow change owing to the various slow motions of the Earth's rotation axis with respect to the fixed stars, and as such it is defined as 'ROTATING.' For details about implications of the rotation state definition, please refer to reference [1]. \begindata FRAME_SOLO_GAE = -144995 FRAME_-144995_NAME = 'SOLO_GAE' FRAME_-144995_CLASS = 5 FRAME_-144995_CLASS_ID = -144995 FRAME_-144995_CENTER = 399 FRAME_-144995_RELATIVE = 'J2000' FRAME_-144995_DEF_STYLE = 'PARAMETERIZED' FRAME_-144995_FAMILY = 'MEAN_ECLIPTIC_AND_EQUINOX_OF_DATE' FRAME_-144995_PREC_MODEL = 'EARTH_IAU_1976' FRAME_-144995_OBLIQ_MODEL = 'EARTH_IAU_1980' FRAME_-144995_FREEZE_EPOCH = @2000-JAN-1/12:00:00.000 \begintext Geocentric Solar Ecliptic (SOLO_GSE) Frame ------------------------------------------------------------------------ Definition: ----------- The Heliocentric Aries Ecliptic frame is defined as follows (from [5]): Definition of the Geocentric Solar Ecliptic frame: All vectors are geometric: no aberration corrections are used. The position of the sun relative to the earth is the primary vector: the X axis points from the earth to the sun. The northern surface normal to the mean ecliptic of date is the secondary vector: the Z axis is the component of this vector orthogonal to the X axis. The Y axis is Z cross X, completing the right-handed reference frame. \begindata FRAME_SOLO_GSE = -144996 FRAME_-144996_NAME = 'SOLO_GSE' FRAME_-144996_CLASS = 5 FRAME_-144996_CLASS_ID = -144996 FRAME_-144996_CENTER = 399 FRAME_-144996_RELATIVE = 'J2000' FRAME_-144996_DEF_STYLE = 'PARAMETERIZED' FRAME_-144996_FAMILY = 'TWO-VECTOR' FRAME_-144996_PRI_AXIS = 'X' FRAME_-144996_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144996_PRI_OBSERVER = 'EARTH' FRAME_-144996_PRI_TARGET = 'SUN' FRAME_-144996_PRI_ABCORR = 'NONE' FRAME_-144996_SEC_AXIS = 'Z' FRAME_-144996_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144996_SEC_FRAME = 'EARTH_MECL_MEQX' FRAME_-144996_SEC_SPEC = 'RECTANGULAR' FRAME_-144996_SEC_VECTOR = ( 0, 0, 1 ) FRAME_-144996_FREEZE_EPOCH = @2000-JAN-1/12:00:00.000 \begintext Heliocentric Earth Ecliptic (SOLO_HEE) Frame ------------------------------------------------------------------------ Definition of the Heliocentric Earth Ecliptic frame: All vectors are geometric: no aberration corrections are used. The position of the earth relative to the sun is the primary vector: the X axis points from the sun to the earth. The northern surface normal to the mean ecliptic of date is the secondary vector: the Z axis is the component of this vector orthogonal to the X axis. The Y axis is Z cross X, completing the right-handed reference frame. \begindata FRAME_SOLO_HEE = -144997 FRAME_-144997_NAME = 'SOLO_HEE' FRAME_-144997_CLASS = 5 FRAME_-144997_CLASS_ID = -144997 FRAME_-144997_CENTER = 10 FRAME_-144997_RELATIVE = 'J2000' FRAME_-144997_DEF_STYLE = 'PARAMETERIZED' FRAME_-144997_FAMILY = 'TWO-VECTOR' FRAME_-144997_PRI_AXIS = 'X' FRAME_-144997_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144997_PRI_OBSERVER = 'SUN' FRAME_-144997_PRI_TARGET = 'EARTH' FRAME_-144997_PRI_ABCORR = 'NONE' FRAME_-144997_SEC_AXIS = 'Z' FRAME_-144997_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144997_SEC_FRAME = 'EARTH_MECL_MEQX' FRAME_-144997_SEC_SPEC = 'RECTANGULAR' FRAME_-144997_SEC_VECTOR = ( 0, 0, 1 ) FRAME_-144997_FREEZE_EPOCH = @2000-JAN-1/12:00:00.000 \begintext Mean Ecliptic of Date Frame (SOLO_ECLIPDATE) ------------------------------------------------------------------------ Definition: ----------- The Mean Ecliptic of Date frame is defined as follows (from[17]): - +X axis is the first point in Aries for the mean ecliptic of date; - +Z axis points along the ecliptic north pole; - +Y axis completes the right-handed system; - the origin of this frame is the Earth's center of mass. All vectors are geometric: no aberration corrections are used. This reference frame can be used to realize the HAE coordinate system by using the sun as the observing body. \begindata FRAME_SOLO_ECLIPDATE = -144980 FRAME_-144980_NAME = 'SOLO_ECLIPDATE' FRAME_-144980_CLASS = 5 FRAME_-144980_CLASS_ID = -144980 FRAME_-144980_CENTER = 399 FRAME_-144980_RELATIVE = 'J2000' FRAME_-144980_DEF_STYLE = 'PARAMETERIZED' FRAME_-144980_FAMILY = 'MEAN_ECLIPTIC_AND_EQUINOX_OF_DATE' FRAME_-144980_PREC_MODEL = 'EARTH_IAU_1976' FRAME_-144980_OBLIQ_MODEL = 'EARTH_IAU_1980' FRAME_-144980_ROTATION_STATE = 'ROTATING' \begintext Geocentric Solar Ecliptic Frame (SOLO_GSE) ------------------------------------------------------------------------ Definition: ---------- The Geocentric Solar Ecliptic frame is defined as follows (from[17]): - +X axis points from the Earth to the Sun; - + Z axis is the otrhogonal component to the +X axis of the northern surface normal to the mean ecliptic of date; - +Y axis completes the right-handed system; - the origin of this frame is the Earth's center of mass. All vectors are geometric: no aberration corrections are used. \begindata FRAME_SOLO_GSE = -144981 FRAME_-144981_NAME = 'SOLO_GSE' FRAME_-144981_CLASS = 5 FRAME_-144981_CLASS_ID = -144981 FRAME_-144981_CENTER = 399 FRAME_-144981_RELATIVE = 'J2000' FRAME_-144981_DEF_STYLE = 'PARAMETERIZED' FRAME_-144981_FAMILY = 'TWO-VECTOR' FRAME_-144981_PRI_AXIS = 'X' FRAME_-144981_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144981_PRI_OBSERVER = 'EARTH' FRAME_-144981_PRI_TARGET = 'SUN' FRAME_-144981_PRI_ABCORR = 'NONE' FRAME_-144981_SEC_AXIS = 'Z' FRAME_-144981_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144981_SEC_FRAME = 'SOLO_ECLIPDATE' FRAME_-144981_SEC_SPEC = 'RECTANGULAR' FRAME_-144981_SEC_VECTOR = ( 0, 0, 1 ) \begintext Heliocentric Inertial frame (SOLO_HCI) ------------------------------------------------------------------------ Definition: ----------- The Heliocentric Inertial frame is defined as follows (from[17]): - +Z points in the solar north direction: the solar rotation axis (IAU_SUN frozen at J2000 epoch); - +X axis is the the ascending node on the ecliptic of J2000 of the IAU_SUN equator. This is accomplished by using the +Z axis of the ecliptic of J2000 as the secondary vector and HCI +Y as the secondary axis - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. \begindata FRAME_SOLO_HCI = -144982 FRAME_-144982_NAME = 'SOLO_HCI' FRAME_-144982_CLASS = 5 FRAME_-144982_CLASS_ID = -144982 FRAME_-144982_CENTER = 10 FRAME_-144982_RELATIVE = 'J2000' FRAME_-144982_DEF_STYLE = 'PARAMETERIZED' FRAME_-144982_FAMILY = 'TWO-VECTOR' FRAME_-144982_FREEZE_EPOCH = @2000-JAN-01/12:00:00 FRAME_-144982_PRI_AXIS = 'Z' FRAME_-144982_PRI_VECTOR_DEF = 'CONSTANT' FRAME_-144982_PRI_FRAME = 'IAU_SUN' FRAME_-144982_PRI_SPEC = 'RECTANGULAR' FRAME_-144982_PRI_VECTOR = ( 0, 0, 1 ) FRAME_-144982_SEC_AXIS = 'Y' FRAME_-144982_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144982_SEC_FRAME = 'ECLIPJ2000' FRAME_-144982_SEC_SPEC = 'RECTANGULAR' FRAME_-144982_SEC_VECTOR = ( 0, 0, 1 ) \begintext Heliocentric Earth Ecliptic frame (SOLO_HEE_NASA) ------------------------------------------------------------------------ Definition: ----------- The Heliocentric Earth Ecliptic frame is defined as follows (from[17]): - +X axis points from the Earth to the Sun; - +Z axis is the component orthogonal to the +X axis of the northern surface normal to the mean ecliptic of date; - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. \begindata FRAME_SOLO_HEE_NASA = -144983 FRAME_-144983_NAME = 'SOLO_HEE_NASA' FRAME_-144983_CLASS = 5 FRAME_-144983_CLASS_ID = -144983 FRAME_-144983_CENTER = 10 FRAME_-144983_RELATIVE = 'J2000' FRAME_-144983_DEF_STYLE = 'PARAMETERIZED' FRAME_-144983_FAMILY = 'TWO-VECTOR' FRAME_-144983_PRI_AXIS = 'X' FRAME_-144983_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144983_PRI_OBSERVER = 'SUN' FRAME_-144983_PRI_TARGET = 'EARTH' FRAME_-144983_PRI_ABCORR = 'NONE' FRAME_-144983_SEC_AXIS = 'Z' FRAME_-144983_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144983_SEC_FRAME = 'SOLO_ECLIPDATE' FRAME_-144983_SEC_SPEC = 'RECTANGULAR' FRAME_-144983_SEC_VECTOR = ( 0, 0, 1 ) \begintext Heliocentric Earth Equatorial frame (SOLO_HEEQ) ------------------------------------------------------------------------ Definition: ----------- The Heliocentric Earth Equatorial frame is defined as follows (from[17]): - +Z points in the solar north direction: the solar rotation axis; - +X is the orthogonal to the +Z axis component of the position of the Earth relative to the Sun; - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. \begindata FRAME_SOLO_HEEQ = -144984 FRAME_-144984_NAME = 'SOLO_HEEQ' FRAME_-144984_CLASS = 5 FRAME_-144984_CLASS_ID = -144984 FRAME_-144984_CENTER = 10 FRAME_-144984_RELATIVE = 'J2000' FRAME_-144984_DEF_STYLE = 'PARAMETERIZED' FRAME_-144984_FAMILY = 'TWO-VECTOR' FRAME_-144984_PRI_AXIS = 'Z' FRAME_-144984_PRI_VECTOR_DEF = 'CONSTANT' FRAME_-144984_PRI_FRAME = 'IAU_SUN' FRAME_-144984_PRI_SPEC = 'RECTANGULAR' FRAME_-144984_PRI_VECTOR = ( 0, 0, 1 ) FRAME_-144984_SEC_AXIS = 'X' FRAME_-144984_SEC_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144984_SEC_OBSERVER = 'SUN' FRAME_-144984_SEC_TARGET = 'EARTH' FRAME_-144984_SEC_ABCORR = 'NONE' FRAME_-144984_SEC_FRAME = 'IAU_SUN' \begintext Geocentric Radial Tangential Normal Frame (SOLO_GEORTN) ------------------------------------------------------------------------ Definition: ----------- The Geocentric RTN frame is defined as follows (from[17]): - +Z the component of the solar north direction perpendicular to the +X axis (+Z is the secondary axis and is the solar rotation axis); - +X points from the Sun center to Earth (primary axis); - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. \begindata FRAME_SOLO_GEORTN = -144985 FRAME_-144985_NAME = 'SOLO_GEORTN' FRAME_-144985_CLASS = 5 FRAME_-144985_CLASS_ID = -144985 FRAME_-144985_CENTER = 10 FRAME_-144985_RELATIVE = 'J2000' FRAME_-144985_DEF_STYLE = 'PARAMETERIZED' FRAME_-144985_FAMILY = 'TWO-VECTOR' FRAME_-144985_PRI_AXIS = 'X' FRAME_-144985_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-144985_PRI_OBSERVER = 'SUN' FRAME_-144985_PRI_TARGET = 'EARTH' FRAME_-144985_PRI_ABCORR = 'NONE' FRAME_-144985_PRI_FRAME = 'IAU_SUN' FRAME_-144985_SEC_AXIS = 'Z' FRAME_-144985_SEC_VECTOR_DEF = 'CONSTANT' FRAME_-144985_SEC_FRAME = 'IAU_SUN' FRAME_-144985_SEC_SPEC = 'RECTANGULAR' FRAME_-144985_SEC_VECTOR = ( 0, 0, 1 ) \begintext Sun Generic Frame Definitions ------------------------------------------------------------------------------ This section contains the definition of the Sun generic frames. Heliocentric Aries Ecliptic of Date frame (SUN_ARIES_ECL) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the Heliocentric Aries Ecliptic of Date frame is referred as SUN_ARIES_ECL. In literature, this frame is referred as HAE (from [13]), or Solar Ecliptic Coordinate System, SE (from [14]). Definition: ----------- The Heliocentric Aries Ecliptic frame is defined as follows (from [4]): - +Z axis is aligned with the north-pointing vector normal to the mean orbital plane of the Earth; - +X axis points toward the first point of Aries, i.e. along the "mean equinox", which is defined as the intersection of the Earth's mean orbital plane with the Earth's mean equatorial plane. It is aligned with the cross product of the north-pointing vectors normal to the Earth's mean equator and mean orbit plane of date; - +Y axis is the cross product of the Z and X axes and completes the right-handed frame; - the origin of this frame is the Sun's center of mass. In [8] this frame is defined equivalent to SOLO_GAE where the center of the frame is the Earth instead of the Sun as the definition suggests. Whilst waiting for final confirmation from NAIF, the frame has been re-defined to be equivalent to SOLO_GAE but with its origin on the Sun. SUN_ARIES_ECL cannot be defined directly as SOLO_GAE with a different CENTER for the following SPICE Error is generated: SPICE(INVALIDSELECTION) Definition of frame SUN_ARIES_ECL specifies frame center SUN and precession model EARTH_IAU_1976. This precession model is not applicable to body SUN. This situation is usually caused by an error in a frame kernel in which the frame is defined. pxform_c --> PXFORM --> REFCHG --> ROTGET --> ZZDYNROT Please note that is also true that the origin of frames in SPICE is not relevant for any computation since they are independent of the vector's origins.s Therefore the frames is defined as a TK frame as follows: \begindata FRAME_SUN_ARIES_ECL = 1000010000 FRAME_1000010000_NAME = 'SUN_ARIES_ECL' FRAME_1000010000_CLASS = 4 FRAME_1000010000_CLASS_ID = 1000010000 FRAME_1000010000_CENTER = 10 TKFRAME_1000010000_SPEC = 'ANGLES' TKFRAME_1000010000_RELATIVE = 'SOLO_GAE' TKFRAME_1000010000_ANGLES = ( 0, 0, 0 ) TKFRAME_1000010000_AXES = ( 3, 2, 1 ) TKFRAME_1000010000_UNITS = 'DEGREES' \begintext Heliocentric Earth Ecliptic frame (SUN_EARTH_ECL) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the Heliocentric Earth Ecliptic frame is referred as SUN_EARTH_ECL. In literature, this frame is referred as HEE (from [15]). Definition: ----------- The Heliocentric Earth Ecliptic frame is defined as follows (from [15]): - X-Y plane is defined by the Earth Mean Ecliptic plane of date, therefore, the +Z axis is the primary vector,and it defined as the normal vector to the Ecliptic plane that points toward the north pole of date; - +X axis is the component of the Sun-Earth vector that is orthogonal to the +Z axis; - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. Required Data: -------------- This frame is defined as a two-vector frame using two different types of specifications for the primary and secondary vectors. The primary vector is defined as a constant vector in the Earth mean ecliptic and equinox of date (EARTH_MECL_MEQX) frame and therefore the definition of this frame have to be loaded before using this frame. The secondary vector is defined as an 'observer-target position' vector, therefore, the ephemeris data required to compute the Sun-Earth vector in J2000 frame have to be loaded prior to using this frame. Remarks: -------- SPICE imposes a constraint in the definition of dynamic frames (see [1]): When the definition of a parameterized dynamic frame F1 refers to a second frame F2 the referenced frame F2 may be dynamic, but F2 must not make reference to any dynamic frame. If F2 is not dynamic but its evaluation requires evaluation of a dynamic frame F3, the same restrictions apply to F3. Therefore, no other dynamic frame should make reference to this frame. Since the secondary vector of this frame is defined as an 'observer-target position' vector, the usage of different planetary ephemerides leads to different implementations of this frame, but only when these data lead to different projections of the Sun-Earth vector on the Earth Ecliptic plane of date. It is strongly recommended to indicate what data have been used in the evaluation of this frame when referring to it, e.g. SUN_EARTH_ECL using de405 ephemerides. As an example, note that the average difference in position of the +X axis of this frame, when using de405 vs. de403 ephemerides, is about 14.3 micro-radians, with a maximum of 15.0 micro-radians. \begindata FRAME_SUN_EARTH_ECL = 1000010002 FRAME_1000010002_NAME = 'SUN_EARTH_ECL' FRAME_1000010002_CLASS = 5 FRAME_1000010002_CLASS_ID = 1000010002 FRAME_1000010002_CENTER = 10 FRAME_1000010002_RELATIVE = 'J2000' FRAME_1000010002_DEF_STYLE = 'PARAMETERIZED' FRAME_1000010002_FAMILY = 'TWO-VECTOR' FRAME_1000010002_PRI_AXIS = 'Z' FRAME_1000010002_PRI_VECTOR_DEF = 'CONSTANT' FRAME_1000010002_PRI_FRAME = 'EARTH_MECL_MEQX' FRAME_1000010002_PRI_SPEC = 'RECTANGULAR' FRAME_1000010002_PRI_VECTOR = ( 0, 0, 1 ) FRAME_1000010002_SEC_AXIS = 'X' FRAME_1000010002_SEC_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_1000010002_SEC_OBSERVER = 'SUN' FRAME_1000010002_SEC_TARGET = 'EARTH' FRAME_1000010002_SEC_ABCORR = 'NONE' \begintext Heliocentric Inertial frame (SUN_INERTIAL) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the Heliocentric Inertial frame is referred as SUN_INERTIAL. In literature, this frame is referred as HCI (from [15]), or Heliographic Inertial, HGI (from [14]). Definition: ----------- The Heliocentric Inertial Frame is defined as follows (from [4]): - X-Y plane is defined by the Sun's equator of epoch J2000: the +Z axis, primary vector, is parallel to the Sun's rotation axis of epoch J2000, pointing toward the Sun's north pole; - +X axis is defined by the ascending node of the Sun's equatorial plane on the ecliptic plane of J2000; - +Y completes the right-handed frame; - the origin of this frame is the Sun's center of mass. Remarks: -------- Note that even when the original frame defined in [15] is referenced to the orientation of the Solar equator in J1900, the SUN_INERTIAL frame is based on J2000 instead. \begindata FRAME_SUN_INERTIAL = 1000010004 FRAME_1000010004_NAME = 'SUN_INERTIAL' FRAME_1000010004_CLASS = 5 FRAME_1000010004_CLASS_ID = 1000010004 FRAME_1000010004_CENTER = 10 FRAME_1000010004_RELATIVE = 'J2000' FRAME_1000010004_DEF_STYLE = 'PARAMETERIZED' FRAME_1000010004_FAMILY = 'TWO-VECTOR' FRAME_1000010004_FREEZE_EPOCH = @2000-JAN-01/12:00:00 FRAME_1000010004_PRI_AXIS = 'Z' FRAME_1000010004_PRI_VECTOR_DEF = 'CONSTANT' FRAME_1000010004_PRI_FRAME = 'IAU_SUN' FRAME_1000010004_PRI_SPEC = 'RECTANGULAR' FRAME_1000010004_PRI_VECTOR = ( 0, 0, 1 ) FRAME_1000010004_SEC_AXIS = 'Y' FRAME_1000010004_SEC_VECTOR_DEF = 'CONSTANT' FRAME_1000010004_SEC_FRAME = 'ECLIPJ2000' FRAME_1000010004_SEC_SPEC = 'RECTANGULAR' FRAME_1000010004_SEC_VECTOR = ( 0, 0, 1 ) \begintext Heliocentric earth equatorial frame (SUN_EARTH_CEQU) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE systems, the Heliocentric Earth Equatorial frame is referred as SUN_EARTH_CEQU. In literature, this frame is referred as HEEQ (from [15] and [13]), or Stonyhurst Heliographic Coordinates (from [6], chapter 2.1) Definition: ----------- The Heliocentric Earth Equatorial frame is defined as follows (from [15] and [13]): - X-Y plane is the solar equator of date, therefore, the +Z axis is the primary vector and it is aligned to the Sun's north pole of date; - +X axis is defined by the intersection between the Sun equatorial plane and the solar central meridian of date as seen from the Earth. The solar central meridian of date is defined as the meridian of the Sun that is turned toward the Earth. Therefore, +X axis is the component of the Sun-Earth vector that is orthogonal to the +Z axis; - +Y axis completes the right-handed system; - the origin of this frame is the Sun's center of mass. All vectors are geometric: no aberration corrections are used. Required Data: -------------- This frame is defined as a two-vector frame using two different types of specifications for the primary and secondary vectors. The primary vector is defined as a constant vector in the IAU_SUN frame, which is a PCK-based frame. Therefore a PCK file containing the orientation constants for the Sun has to be loaded before any evaluation of this frame. The secondary vector is defined as an 'observer-target position' vector. Therefore, the ephemeris data required to compute the Sun-Earth vector in J2000 frame have to be loaded before using this frame. Remarks: -------- This frame is defined based on the IAU_SUN frame, whose evaluation is based on the data included in the loaded PCK file: different orientation constants for the Sun's spin axis will lead to a different frame orientation at a given time. Since the secondary vector of this frame is defined as an 'observer-target position' vector, the usage of different planetary ephemerides conduces to different implementations of this frame, but only when these data lead to different solar central meridians, i.e. the projection of the Sun-Earth vector on the Sun equatorial plane obtained from the different ephemerides has a non-zero angular separation. It is strongly recommended to indicate what data have been used in the evaluation of this frame when referring to it, e.g. SUN_EARTH_CEQU using IAU 2009 constants and de405 ephemerides. Note that the effect of using different SPK files is smaller, in general, that using different Sun's spin axis constants. As an example, the average difference in the position of the +X axis of the frame, when using DE405 or DE403 ephemerides is about 14.3 micro-radians, with a maximum of 15.3 micro-radians. \begindata FRAME_SUN_EARTH_CEQU = 1000010001 FRAME_1000010001_NAME = 'SUN_EARTH_CEQU' FRAME_1000010001_CLASS = 5 FRAME_1000010001_CLASS_ID = 1000010001 FRAME_1000010001_CENTER = 10 FRAME_1000010001_RELATIVE = 'J2000' FRAME_1000010001_DEF_STYLE = 'PARAMETERIZED' FRAME_1000010001_FAMILY = 'TWO-VECTOR' FRAME_1000010001_PRI_AXIS = 'Z' FRAME_1000010001_PRI_VECTOR_DEF = 'CONSTANT' FRAME_1000010001_PRI_FRAME = 'IAU_SUN' FRAME_1000010001_PRI_SPEC = 'RECTANGULAR' FRAME_1000010001_PRI_VECTOR = ( 0, 0, 1 ) FRAME_1000010001_SEC_AXIS = 'X' FRAME_1000010001_SEC_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_1000010001_SEC_OBSERVER = 'SUN' FRAME_1000010001_SEC_TARGET = 'EARTH' FRAME_1000010001_SEC_ABCORR = 'NONE' \begintext Earth Generic Frame Definitions ------------------------------------------------------------------------------ This section contains the definition of the Earth generic frames. Geocentric solar ecliptic of date frame (EARTH_SUN_ECL) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the geocentric solar ecliptic of date frame is referred as EARTH_SUN_ECL. In literature, this frame is referred as GSE (from [15]). Definition: ----------- The Geocentric Solar Ecliptic frame of date is defined as follows (from [15]): - X-Y plane is defined by the Earth Mean Ecliptic plane of date: the +Z axis, primary vector, is the normal vector to this plane, always pointing toward the North side of the invariable plane; - +X axis is the component of the Earth-Sun vector that is orthogonal to the +Z axis; - +Y axis completes the right-handed system; - the origin of this frame is the Earth's center of mass. All the vectors are geometric: no aberration corrections are used. Required Data: -------------- This frame is defined as a two-vector frame using two different types of specifications for the primary and secondary vectors. The primary vector is defined as a constant vector in the Earth mean ecliptic and mean equinox of date frame, and therefore the definition of EARTH_MECL_MEQX has to be loaded before using this frame. The secondary vector is defined as an 'observer-target position' vector, therefore, the ephemeris data required to compute the Earth-Sun vector in J2000 frame have to be loaded prior to using this frame. Remarks: -------- SPICE imposes a constraint in the definition of dynamic frames (see [1]): When the definition of a parameterized dynamic frame F1 refers to a second frame F2 the referenced frame F2 may be dynamic, but F2 must not make reference to any dynamic frame. Therefore, no other dynamic frame should make reference to this frame. Since the secondary vector of this frame is defined as an 'observer-target position' vector, the usage of different planetary ephemerides may lead to a different frame orientation at a given time, but only when these data lead to different projections of the Earth-Sun vector on the Earth mean ecliptic plane of date. It is strongly recommended to indicate what data have been used in the evaluation of this frame when referring to it, e.g. EARTH_SUN_ECL using de405 ephemerides. As an example, note that the average difference in position of the +X axis of this frame, when using de405 vs. de403 ephemerides, is about 14.3 micro-radians, with a maximum of 15.0 micro-radians. \begindata FRAME_EARTH_SUN_ECL = 300399005 FRAME_300399005_NAME = 'EARTH_SUN_ECL' FRAME_300399005_CLASS = 5 FRAME_300399005_CLASS_ID = 300399005 FRAME_300399005_CENTER = 399 FRAME_300399005_RELATIVE = 'J2000' FRAME_300399005_DEF_STYLE = 'PARAMETERIZED' FRAME_300399005_FAMILY = 'TWO-VECTOR' FRAME_300399005_PRI_AXIS = 'Z' FRAME_300399005_PRI_VECTOR_DEF = 'CONSTANT' FRAME_300399005_PRI_FRAME = 'EARTH_MECL_MEQX' FRAME_300399005_PRI_SPEC = 'RECTANGULAR' FRAME_300399005_PRI_VECTOR = ( 0, 0, 1 ) FRAME_300399005_SEC_AXIS = 'X' FRAME_300399005_SEC_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_300399005_SEC_OBSERVER = 'EARTH' FRAME_300399005_SEC_TARGET = 'SUN' FRAME_300399005_SEC_ABCORR = 'NONE' \begintext Earth Mean Ecliptic and Equinox of date frame (EARTH_MECL_MEQX) ------------------------------------------------------------------------ SPICE frame name, common names and other designators: ----------------------------------------------------- Within the SPICE system, the Earth mean ecliptic and equinox of date frame is referred as EARTH_MECL_MEQX. In literature, this frame is referred as mean ecliptic of date (from [16]) Definition: ----------- The Earth mean ecliptic and equinox of date frame is defined as follows (from [16]): - +Z axis is aligned with the north-pointing vector normal to the mean orbital plane of the Earth; - +X axis points along the ``mean equinox'', which is defined as the intersection of the Earth's mean orbital plane with the Earth's mean equatorial plane. It is aligned with the cross product of the north-pointing vectors normal to the Earth's mean equator and mean orbit plane of date; - +Y axis is the cross product of the Z and X axes and completes the right-handed frame; - the origin of this frame is the Earth's center of mass. The mathematical model used to obtain the orientation of the Earth's mean equator and equinox of date frame is the 1976 IAU precession model, built into SPICE. The mathematical model used to obtain the mean orbital plane of the Earth is the 1980 IAU obliquity model, also built into SPICE. The base frame for the 1976 IAU precession model is J2000. Required Data: -------------- The usage of this frame does not require additional data since both the precession and the obliquity models used to define this frame are already built into SPICE. Remarks: -------- None. \begindata FRAME_EARTH_MECL_MEQX = 300399000 FRAME_300399000_NAME = 'EARTH_MECL_MEQX' FRAME_300399000_CLASS = 5 FRAME_300399000_CLASS_ID = 300399000 FRAME_300399000_CENTER = 399 FRAME_300399000_RELATIVE = 'J2000' FRAME_300399000_DEF_STYLE = 'PARAMETERIZED' FRAME_300399000_FAMILY = 'MEAN_ECLIPTIC_AND_EQUINOX_OF_DATE' FRAME_300399000_PREC_MODEL = 'EARTH_IAU_1976' FRAME_300399000_OBLIQ_MODEL = 'EARTH_IAU_1980' FRAME_300399000_ROTATION_STATE = 'ROTATING' \begintext End of FK file.