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SuperNOVAS: include/solarsystem.h File Reference

SuperNOVAS header for custom solar-system ephemeris calculations for major planets plus the Sun, Moon, and the Solar-system barycenter (and as of v1.2 also the Earth-Moon Barycenter and the barycenter of the Pluto system).

The source files solsys-calceph.c and solsys-cspice.c provide implementations that interface with the CALCEPH C library and the NAIF CSPICE Toolkit, respectively. CSPICE is the canocical library for handling JPL (SPK) ephemeris data, while CALCEPH is a more modern tool, which allows handling most types of JPL ephemerides, as well INPOP 2.0/3.0 format data files.

The source files solsys1.c, solsys2.c, solsys3.c and solsys-ephem.c provide various legacy implementations that users may use (some require additional sources, or user-specific implementations).

If the standard implementations are compiled with the DEFAULT_SOLSYS option set (see config.mk), then the library is compiled with that version providing a built-in default implementation (the default is to use solsys3.c, which is a self-contained orbital calculation for the Sun and Earth only).

Additionally, users may set their custom choice of major planet ephemeris handler at runtime via the set_planet_provider() and/or set_planet_provider_hp() functions. They may also define custom handlers for all other types of Solar-system objects (i.e. NOVAS_EPHEM_OBJECT types) via set_ephem_provider().

Based on the NOVAS C Edition, Version 3.1:

U. S. Naval Observatory
Astronomical Applications Dept.
Washington, DC
http://www.usno.navy.mil/USNO/astronomical-applications

See also

solsys-calceph.c

solsys-cspice.c

solsys1.c

solsys2.c

solsys3.c

solsys-ephem.c

Number of different Solar-system body ID types enumerated

See also

enum novas_id_type

Author

Attila Kovacs

Since

1.2

Function to obtain ephemeris data for minor planets, which are not handled by the solarsystem() type calls. The library does not provide a default implementation, but users can provide their own, either as a default statically compiled readeph() implementation, or else a dynamically defined one via ephemeris_set_reader().

Note, that implementations would typically use either the name or the ID argument to identify the object for which ephemeris data is requested. As such you only need to specify the one that is going to be used.

Parameters

name The name of the solar-system body (in case the ephemeris provider supports lookup by name), or NULL to force ID based lookup. id The ID number of the solar-system body for which the position in desired. (Typically a NAIF ID, or else an appropriate ID for the implementation – corresponding minor planet objects should be created with the same type of ID.). A value of -1 can be used to force name based lookups (provided the implementation supports it). jd_tdb_high [day] The high-order part of Barycentric Dynamical Time (TDB) based Julian date for which to find the position and velocity. Typically this may be the integer part of the Julian date for high-precision calculations, or else the entire Julian date for reduced precision. jd_tdb_low [day] The low-order part of Barycentric Dynamical Time (TDB) based Julian date for which to find the position and velocity. Typically this may be the fractional part of the Julian date for high-precision calculations, or else 0.0 if the date is defined entirely by the high-order component for reduced precision. [out] origin Set to NOVAS_BARYCENTER or NOVAS_HELIOCENTER to indicate relative to which the ephemeris positions/velocities are reported. [out] pos [AU] position 3-vector to populate with rectangular equatorial coordinates in AU. It may be NULL if position is not required. [out] vel [AU/day] velocity 3-vector to populate in rectangular equatorial coordinates in AU/day. It may be NULL if velocities are not required.

Returns

0 if successful, -1 if any of the pointer arguments are NULL, or some non-zero value if the was an error s.t. the position and velocity vector should not be used.

See also

set_ephem_provider()

ephemeris()

NOVAS_EPHEM_OBJECT

solsys-ephem.c

Since

1.0

Author

Attila Kovacs

Provides the position and velocity of major planets (as well as the Sun, Moon, Solar-system Barycenter, and other barycenters). This version provides positions and velocities at regular precision (see NOVAS_REDUCED_PRECISION).

Since this is a function that may be provided by existing custom user implementations, we keep the original argument types for compatibility, hence 'short' instead of the more informative enums).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date body Major planet number (or that for the Sun, Moon, or an appropriate barycenter), as defined by enum novas_planet, e.g. NOVAS_MARS (4), NOVAS_SUN (10) or NOVAS_SSB (0). origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS), 1 if the input Julian date ('tjd') is out of range, 2 if 'body' is invalid, or 3 if the ephemeris data cannot be produced for other reasons.

See also

set_planet_provider()

ephemeris()

novas_solarsystem_hp_func

Since

1.0

Author

Attila Kovacs

Provides the position and velocity of major planets (as well as the Sun, Moon, Solar-system Barycenter, and other barycenters). This version provides positions and velocities at high precision (see NOVAS_FULL_PRECISION).

Since this is a function that may be provided by existing custom user implementations, we keep the original argument types for compatibility, hence 'short' instead of the more informative enums).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date, broken into high and low order components, respectively. Typically, as the integer and fractional parts for the highest precision. body Major planet number (or that for the Sun, Moon, or an appropriate barycenter), as defined by enum novas_planet, e.g. NOVAS_MARS (4), NOVAS_SUN (10) or NOVAS_SSB (0). origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS), 1 if the input Julian date ('tjd') is out of range, 2 if 'body' is invalid, or 3 if the ephemeris data cannot be produced for other reasons.

See also

set_planet_provider_hp()

novas_solarsystem_func

ephemeris()

Since

1.0

Author

Attila Kovacs

Solar-system body IDs to use as object.number with NOVAS_EPHEM_OBJECT types. JPL ephemerides use NAIF IDs to identify objects in the Solar-system, which is thus the most widely adopted convention for numbering Solar-system bodies. But other numbering systems also exists, for example the CALCEPH library uses its own convention for the numbering of asteroids.

See also

object

NOVAS_EPHEM_OBJECT

NOVAS_ID_TYPES

Author

Attila Kovacs

Since

1.2

If the ephemeris provider should use NAIF IDs.

If the ephemeris provider should use CALCEPH IDs.

Provides the position and velocity of the Earth and Sun only at epoch 'jd_tdb' by evaluating a closed-form theory without reference to an external file. This function can also provide the position and velocity of the Sun.

REFERENCES:

1. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.
2. Explanatory Supplement to The Astronomical Almanac (1992).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date body NOVAS_EARTH (3) or NOVAS_SUN (10) only. origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS) or if one of the output pointer arguments is NULL (errno set to EINVAL). 1 if the input Julian date ('tjd') is out of range, 2 if 'body' is invalid.

See also

earth_sun_calc_hp()

set_planet_provider()

solarsystem()

novas_planet_provider

References NOVAS_BARYCENTER, NOVAS_EARTH, NOVAS_PLANETS, NOVAS_SSB, NOVAS_SUN, precession(), radec2vector(), sun_eph(), and TWOPI.

It may provide the position and velocity of the Earth and Sun, the same as solarsystem_earth_sun(), if enable_earth_sun_hp() is set to true (non-zero). Otherwise, it will return with an error code of 3, indicating that high-precision calculations are not provided by this implementation.

NOTES:

1. This implementation will always propulate the output position and velocity vectors with the low-precision result, regardless of the return error code, in order to reduce the chance of unpredictable behavior, even if the user does not check the returned error status (which of course they should).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date body NOVAS_EARTH (3) or NOVAS_SUN (10) only. origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS), or if one of the output pointer arguments is NULL (errno set to EINVAL). 1 if the input Julian date ('tjd') is out of range, 2 if 'body' is invalid, or 3 if the high-precision orbital data cannot be produced (default return value).

See also

enable_earth_sun_hp()

earth_sun_calc()

set_planet_provider()

solarsystem_hp()

novas_planet_provider_hp

References earth_sun_calc().

Specify whether the high-precision call is allowed to return a low-precision result. If set to 0 (false) solarsystem_earth_sun_hp() will return with an error code 3 indicating that a high-precision calculation is not possible. Otherise, a non-zero value (true) will let the function to be used without errors, returning the low-precison result of solarsystem_earth_sun() instead.

Parameters

value (boolean) A non-zero value enables the error-free use of the earth_sun_calc_hp() by allowing to return the low-precision result. Otherwise, earth_sun_calc_hp() will return an error code 3 indicating that the high-precision result is not available (this latter is the default behavior).

See also

earth_sun_calc_hp()

Sets a celestial object to be a Solar-system orbital body. Typically this would be used to define minor planets, asteroids, comets, or even planetary satellites.

Parameters

name Name of object. It may be NULL if not relevant. num Solar-system body ID number (e.g. NAIF). It is not required and can be set e.g. to -1 if not relevant to the caller. orbit The orbital parameters to adopt. The data will be copied, not referenced. [out] body Pointer to structure to populate.

Returns

0 if successful, or else -1 if the 'orbit' or 'body' pointer is NULL or the name is too long.

See also

novas_orbit_posvel()

make_planet()

make_ephem_object()

novas_geom_posvel()

place()

Since

1.2

Author

Attila Kovacs

References make_object(), NOVAS_ORBITAL_OBJECT, and object::orbit.

Converts a NAIF ID to a NOVAS major planet ID. It account for the different IDs used for Sun, Moon, SSB, EMB and the Pluto system. Otherwise NAIF planet barycenters are mapped to the corresponding bodies. NAIF body centers n99 (e.g. 399 for Earth) are mapped to the corresponding NOVAS planet number n. All other NAIF IDs will return -1, indicating no match to a NOVAS planet ID.

Parameters

id The NAIF ID of the major planet of interest

Returns

the NOVAS ID for the same object (which may or may not be different from the input), or -1 if the NAIF ID cannot be matched to a NOVAS major planet.

See also

novas_to_naif_planet()

novas_to_dexxx_planet()

Author

Attila Kovacs

Since

1.2

References NOVAS_EMB, NOVAS_MERCURY, NOVAS_MOON, NOVAS_PLUTO, NOVAS_PLUTO_BARYCENTER, NOVAS_SSB, and NOVAS_SUN.

Returns the approximate geometric heliocentric orbital positions and velocities for the major planets, Sun, or Earth-Moon Barycenter (EMB). The returned positions and velocities are not suitable for precise calculations. However, they may be used to provide rough guidance about the approximate locations of the planets, e.g. for determining approximate rise or set times or the approximate azimuth / elevation angles from an observing site.

The orbitals can provide planet positions to arcmin-level precision for the rocky inner planets, and to a fraction of a degree precision for the gas and ice giants and Pluto. The accuracies for Uranus, Neptune, and Pluto are significantly improved (to the arcmin level) if used in the time range of 1800 AD to 2050 AD. For a more detailed summary of the typical accuracies, see either of the top two references below.

For accurate positions, you should use planetary ephemerides (such as the JPL ephemerides via the CALCEPH or CSPICE plugins) and novas_geom_posvel() instead.

While this function is generally similar to creating an orbital object with an orbit initialized with novas_make_planet_orbit() or novas_make_moon_orbit(), and then calling novas_geom_posvel(), there are a few important differences:

1. This function returns geometric positions referenced to the Sun (i.e., heliocentric), whereas novas_geom_posvel() references the calculated positions to the Solar-system Barycenter (SSB).
2. This function calculates Earth and Moon positions about the Keplerian orbital position of the Earth-Moon Barycenter (EMB). In constrast, novas_make_planet_orbit() does not provide orbitals for the Earth directly, and make_moot_orbit() references the Moon's orbital to the Earth position returned by the currently configured planet calculator function (see set_planet_provider()).

NOTES:

1. The Sun's position w.r.t. the Solar-system Barycenter is calculated using earth_sun_calc(). All other orbitals are also referenced to the Sun's position calculated that way.

REFERENCES:

1. E.M. Standish and J.G. Williams 1992.
2. https://ssd.jpl.nasa.gov/planets/approx_pos.html
3. Chapront, J. et al., 2002, A&A 387, 700–709
4. Chapront-Touze, M, and Chapront, J. 1983, Astronomy and Astrophysics (ISSN 0004-6361), vol. 124, no. 1, July 1983, p. 50-62.

Parameters

id NOVAS major planet ID. All major planets, plus the Sun, Moon, Earth-Moon Barycenter (EMB), and Pluto system Barycenter are supported. (For Pluto, the Pluto System Barycenter value are returned.) jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian Date. Dates between 3000 BC and 3000 AD are supported. For dates between 1800 AD and 2050 AD the returned positions are somewhat more accurate. [out] pos [AU] Output Heliocentric ICRS position vector, or NULL if not required. [out] vel [AU/day] Output Heliocentric ICRS velocity vector, or NULL if not required.

Returns

0 if successful, or if the JD date is outside of the range with valid parameters, or else -1 if the planet ID is not supported or if both output vectors are NULL. In case of errors errno will be set to indicate the type of error.

Since

1.4

Author

Attila Kovacs

See also

novas_approx_sky_pos()

earth_sun_calc()

novas_geom_posvel()

novas_use_calceph()

novas_use_cspice()

References NOVAS_EARTH, NOVAS_EMB, novas_make_moon_orbit(), novas_make_planet_orbit(), NOVAS_MOON, NOVAS_ORBIT_INIT, novas_orbit_posvel(), NOVAS_REDUCED_ACCURACY, and NOVAS_SUN.

Calculates an approximate apparent location on sky for a major planet, Sun, Moon, Earth-Moon Barycenter (EMB) – typically to arcmin level accuracy – using Keplerian orbital elements. The returned position is antedated for light-travel time (for Solar-System bodies). It also applies an appropriate aberration correction (but not gravitational deflection).

The orbitals can provide planet positions to arcmin-level precision for the rocky inner planets, and to a fraction of a degree precision for the gas and ice giants and Pluto. The accuracies for Uranus, Neptune, and Pluto are significantly improved (to the arcmin level) if used in the time range of 1800 AD to 2050 AD. For a more detailed summary of the typical accuracies, see either of the top two references below.

For accurate positions, you should use planetary ephemerides (such as the JPL ephemerides via the CALCEPH or CSPICE plugins) and novas_sky_pos() instead.

While this function is generally similar to creating an orbital object with an orbit initialized with novas_make_planet_orbit() or novas_make_moon_orbit(), and then calling novas_sky_pos(), there are a few important differences to note:

1. This function calculates Earth and Moon positions about the Keplerian orbital position of the Earth-Moon Barycenter (EMB). In constrast, novas_make_planet_orbit() does not provide orbitals for the Earth directly, and make_moot_orbit() references the Moon's orbital to the Earth position returned by the currently configured planet calculator function (see set_planet_provider()).
2. This function ignores gravitational deflection. It makes little sense to bother about corrections that are orders of magnitude below the accuracy of the orbital positions obtained.

REFERENCES:

1. E.M. Standish and J.G. Williams 1992.
2. https://ssd.jpl.nasa.gov/planets/approx_pos.html
3. Chapront, J. et al., 2002, A&A 387, 700–709
4. Chapront-Touze, M, and Chapront, J. 1983, Astronomy and Astrophysics (ISSN 0004-6361), vol. 124, no. 1, July 1983, p. 50-62.

Parameters

id NOVAS major planet ID. All major planets, plus the Sun, Moon, Earth-Moon Barycenter (EMB), and Pluto system Barycenter are supported. (For Pluto, the Pluto System Barycenter values are returned.) frame The observer frame, defining the location and time of observation. sys The coordinate system in which to return the apparent sky location. [out] out Pointer to the data structure which is populated with the calculated approximate apparent location in the designated coordinate system.

Returns

0 if successful, or else -1 in case of an error (errno will indicate the type of error).

Since

1.4

Author

Attila Kovacs

See also

novas_sky_pos()

novas_app_to_hor()

make_frame()

References make_planet(), novas_approx_heliocentric(), novas_geom_to_app(), novas_get_time(), NOVAS_TDB, novas_vlen(), and rad_vel2().

Returns a Solar-system body's distance from the Sun, and optionally also the rate of recession. It may be useful, e.g. to calculate the body's heating from the Sun.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date. You may want to use a time that is antedated to when the observed light originated from the source. source Observed Solar-system source [out] rate [AU/day] (optional) Returned rate of recession from Sun

Returns

[AU] Distance from the Sun, or NAN if not a Solar-system source.

Since

1.3

Author

Attila Kovacs

See also

novas_solar_power()

novas_solar_illum()

References ephemeris(), NOVAS_CATALOG_OBJECT, NOVAS_HELIOCENTER, NOVAS_REDUCED_ACCURACY, and novas_vlen().

Gets the current orbital elements for the Moon relative to the geocenter for the specified epoch of observation.

REFERENCES:

1. Chapront, J. et al., 2002, A&A 387, 700–709
2. Chapront-Touze, M, and Chapront, J. 1983, Astronomy and Astrophysics (ISSN 0004-6361), vol. 124, no. 1, July 1983, p. 50-62.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian Date. [out] orbit Orbital elements data structure to populate.

Returns

0 if successful, or else -1 (errno set to EINVAL).

Since

1.4

Author

Attila Kovacs

See also

novas_make_planet_orbit()

make_orbital_object()

References NOVAS_AU, NOVAS_EARTH, NOVAS_JD_J2000, NOVAS_ORBIT_INIT, and TWOPI.

Get approximate current heliocentric orbital elements for the major planets. These orbital elements are not suitable for precise position velocity calculations, but they may be useful to obtain approximate positions for the major planets, e.g. to estimate rise or set times, or apparent elevation angles from an observing site.

These orbitals can provide planet positions to arcmin-level precision for the rocky inner planets, and to a fraction of a degree precision for the gas and ice giants and Pluto. The accuracies for Uranus, Neptune, and Pluto are significantly improved (to the arcmin level) if used in the time range of 1800 AD to 2050 AD. For a more detailed summary of the typical accuracies, see either of the references below.

NOTES:

1. The Earth-Moon system is treated as a single orbital of the Earth-Moon Barycenter (EMB). That is, the EMB orbital is returned for both Earth and the Moon also.
2. For Pluto, the Pluto system barycenter orbit is returned.

REFERENCES:

1. E.M. Standish and J.G. Williams 1992.
2. https://ssd.jpl.nasa.gov/planets/approx_pos.html

Parameters

id NOVAS major planet ID. All major planets, except Earth, are supported. The Earth-Moon Barycenter (EMB), and Pluto system Barycenter are supported also. (For Pluto, the Pluto System Barycenter values are returned.) jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian Date. [out] orbit Orbital elements data structure to populate.

Returns

0 if successful, or else -1 (errno set to EINVAL).

Since

1.4

Author

Attila Kovacs

See also

novas_make_moon_orbit()

novas_approx_sky_pos()

novas_approx_heliocentric()

make_orbital_object()

Keplerian orbital elements at J2000 from Table 8.10.2 of E.M. Standish and J.G. Williams 1992, valid for 1800 AD to 2050 AD.

Temporal evolution of the Keplerian orbital elements from Table 8.10.2 of E.M. Standish and J.G. Williams 1992, valid for 1800 AD to 2050 AD.

Keplerian orbital elements at J2000 from Table 8.10.3 of E.M. Standish and J.G. Williams 1992, valid for 3000 BC to 3000 AD.

Temporal evolution of the Keplerian orbital elements from Table 8.10.3 of E.M. Standish and J.G. Williams 1992, vaid for 3000 BC to 3000 AD.

Additional terms for computing M for the outer planets (Jupiter and beyond) from Table 8.10.4 of E.M. Standish and J.G. Williams 1992.

References NOVAS_EARTH, NOVAS_EMB, NOVAS_JD_J2000, NOVAS_JUPITER, NOVAS_ORBIT_INIT, NOVAS_PLUTO, NOVAS_PLUTO_BARYCENTER, and TWOPI.

Returns the apparent angular distance of a source from the Moon from the observer's point of view.

Parameters

source An observed source frame Observing frame, defining the observer location and astronomical time of observation.

Returns

[deg] Apparent angular distance between the source an the Moon, from the observer's point of view

Since

1.3

Author

Attila Kovacs

See also

novas_sun_angle()

References NOVAS_MOON_INIT, and novas_object_sep().

Calculates the Moon's phase at a given time. It uses orbital models for Earth (E.M. Standish and J.G. Williams 1992), and for the Moon (Chapront, J. et al., 2002), and takes into account the slightly eccentric nature of both orbits.

NOTES:

1. The Moon's phase here follows the definition by the Astronomical Almanac, as the excess ecliptic longitude of the Moon over that of the Sun seen from the geocenter.
2. There are other definitions of the phase too, depending on which you might find slightly different answers, but regardless of the details most phase calculations should match to within a few degrees.

REFERENCES:

1. The Explanatory Supplement to the Astronomical Almanac, University Science Books, 3rd ed., p. 507
2. E.M. Standish and J.G. Williams 1992.
3. https://ssd.jpl.nasa.gov/planets/approx_pos.html
4. Chapront, J. et al., 2002, A&A 387, 700–709
5. Chapront-Touze, M, and Chapront, J. 1983, Astronomy and Astrophysics (ISSN 0004-6361), vol. 124, no. 1, July 1983, p. 50-62.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian Date.

Returns

[deg] The Moon's phase, or more precisely the ecliptic longitude difference between the Sun and the Moon, as seen from the geocenter. 0: New Moon, 90: 1st quarter, +/- 180 Full Moon, -90: 3rd quarter or NAN if the solution failed to converge (errno will be set to ECANCELED), or if the JD date is outside the range of the orbital model (errno set to EINVAL).

Since

1.4

Author

Attila Kovacs

See also

novas_next_moon_phase()

novas_make_moon_orbit()

novas_solar_illum()

References NOVAS_EMB, novas_make_moon_orbit(), novas_make_planet_orbit(), NOVAS_ORBIT_INIT, novas_orbit_native_posvel(), and vector2radec().

Calculates the date / time at which the Moon will reach the specified phase next, after the specified time. It uses orbital models for Earth (E.M. Standish and J.G. Williams 1992), and for the Moon (Chapront, J. et al., 2002), and takes into account the slightly eccentric nature of both orbits.

NOTES:

1. The Moon's phase here follows the definition by the Astronomical Almanac, as the excess ecliptic longitude of the Moon over that of the Sun seen from the geocenter.
2. There are other definitions of the phase too, depending on which you might find slightly different answers, but regardless of the details most phase calculations should match give or take a few hours.

REFERENCES:

1. The Explanatory Supplement to the Astronomical Almanac, University Science Books, 3rd ed., p. 507
2. E.M. Standish and J.G. Williams 1992.
3. https://ssd.jpl.nasa.gov/planets/approx_pos.html
4. Chapront, J. et al., 2002, A&A 387, 700–709
5. Chapront-Touze, M, and Chapront, J. 1983, Astronomy and Astrophysics (ISSN 0004-6361), vol. 124, no. 1, July 1983, p. 50-62.

Parameters

phase [deg] The Moon's phase, or more precisely the ecliptic longitude difference between the Sun and the Moon, as seen from the geocenter. 0: New Moon, 90: 1st quarter, +/- 180 Full Moon, -90: 3rd quarter. jd_tdb [day] The lower bound date for the phase, as a Barycentric Dynamical Time (TDB) based Julian Date.

Returns

[day] The Barycentric Dynamical Time (TDB) based Julian Date when the Moon will be in the desired phase next after the input date; or NAN if the solution failed to converge (errno will be set to ECANCELED).

Since

1.4

Author

Attila Kovacs

See also

novas_moon_phase()

novas_make_moon_orbit()

References novas_inv_max_iter, NOVAS_JD_J2000, and novas_moon_phase().

Returns the NOVAS planet ID for a given name (case insensitive), or -1 if no match is found.

Parameters

name The planet name, or that for the "Sun", "Moon" or "SSB" (case insensitive). The spelled out "Solar System Barycenter" is also recognized with either spaces, hyphens ('-') or underscores ('_') separating the case insensitive words.

Returns

The NOVAS major planet ID, or -1 (errno set to EINVAL) if the input name is NULL or if there is no match for the name provided.

Author

Attila Kovacs

Since

1.2

See also

make_planet()

References NOVAS_PLANET_NAMES_INIT, NOVAS_PLANETS, and NOVAS_SSB.

Sets the orientation of an orbital system using the RA and DEC coordinates of the pole of the Laplace (or else equatorial) plane relative to which the orbital elements are defined. Orbital parameters of planetary satellites normally include the R.A. and declination of the pole of the local Laplace plane in which the Keplerian orbital elements are referenced.

The system will become referenced to the equatorial plane, the relative obliquity is set to (90° - dec), while the argument of the ascending node ('Omega') is set to (90° + ra).

NOTES:

1. You should not expect much precision from the long-range orbital approximations for planetary satellites. For applications that require precision at any level, you should rely on appropriate ephemerides, or else on up-to-date short-term orbital elements.

Parameters

type Coordinate reference system in which ra and dec are defined (e.g. NOVAS_GCRS). ra [h] the R.A. of the pole of the oribtal reference plane. dec [deg] the declination of the pole of the oribtal reference plane. [out] sys Orbital system

Returns

0 if successful, or else -1 (errno will be set to EINVAL) if the output sys pointer is NULL.

Author

Attila Kovacs

Since

1.2

See also

make_orbital_object()

References NOVAS_EQUATORIAL_PLANE, and NOVAS_TIRS.

Returns the Solar illumination fraction of a source, assuming a spherical geometry for the observed body.

Parameters

source Observed source. Usually a Solar-system source. (For other source types, 1.0 is returned by default.) frame Observing frame, defining the observer location and astronomical time of observation.

Returns

Solar illumination fraction [0.0:1.0] of a spherical body observed at the source location from the given observer location, or NAN if there was an error (errno will indicate the type of error).

Since

1.3

Author

Attila Kovacs

References NOVAS_CATALOG_OBJECT, novas_geom_posvel(), NOVAS_ICRS, and novas_vlen().

Returns the typical incident Solar power on a Solar-system body at the time of observation.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date. You may want to use a time that is antedated to when the observed light originated ( was reflected) from the source. source Observed Solar-system source

Returns

[W/m²] Incident Solar power on the illuminated side of the object, or NAN if not a Solar-system source or if the source is the Sun itself.

Since

1.3

Author

Attila Kovacs

See also

novas_solar_illum()

References novas_helio_dist(), and NOVAS_SOLAR_CONSTANT.

Returns the apparent angular distance of a source from the Sun from the observer's point of view.

Parameters

source An observed source frame Observing frame, defining the observer location and astronomical time of observation.

Returns

[deg] the apparent angular distance between the source an the Sun, from the observer's point of view

Since

1.3

Author

Attila Kovacs

See also

novas_moon_angle()

References novas_object_sep(), and NOVAS_SUN_INIT.

Converts a NOVAS Solar-system body ID to a NAIF Solar-system body ID for DExxx ephemeris files. The DExxx (e.g. DE440) ephemeris files use NAIF IDs, but for most planets contain barycentric data only rather than that of the planet center. For Earth-based observations, it only really makes a difference whether the 3 is used for the Earth-Moon Barycenter (EMB) or 399 for the geocenter.

Parameters

id The NOVAS ID of the major planet of interest

Returns

the NAIF ID for the same object (which may or may not be different from the input), as appropriate for use in the DExxx ephemeris files.

See also

novas_to_naif_planet()

naif_to_novas_planet()

Author

Attila Kovacs

Since

1.2

References NOVAS_EARTH, NOVAS_EMB, NOVAS_MERCURY, NOVAS_MOON, NOVAS_PLUTO, NOVAS_PLUTO_BARYCENTER, NOVAS_SSB, and NOVAS_SUN.

Converts a NOVAS Solar-system body ID to a NAIF Solar-system body ID. NOVAS and NAIF use slightly different IDs for major planets, the Moon, SSB, EMB, and the Pluto system. In NOVAS, major planets are have IDs ranging from 1 through 9, but for NAIF 1–9 are the planetary barycenters and the planet centers have numbers in the hundreds ending with 99 (e.g. the center of Earth is NAIF 399; 3 is the NOVAS ID for Earth and the NAIF ID for the Earth-Moon Barycenter [EMB]). The Sun and Moon also have distinct IDs in NAIF vs NOVAS.

Parameters

id The NOVAS ID of the major planet of interest

Returns

the NAIF ID for the same object or planet center (which may or may not be different from the input)

See also

naif_to_novas_planet()

Author

Attila Kovacs

Since

1.2

References NOVAS_EMB, NOVAS_MERCURY, NOVAS_MOON, NOVAS_PLUTO, NOVAS_PLUTO_BARYCENTER, NOVAS_SSB, and NOVAS_SUN.

Provides an interface between the JPL direct-access solar system ephemerides and NOVAS-C for regular (reduced) precision applications.

This function and planet_eph_manager_hp() were designed to work with the 1997 version of the JPL ephemerides, as noted in the references.

The user must create the binary ephemeris files using software from JPL, and open the file using function ephem_open(), prior to calling this function.

REFERENCES:

1. JPL. 2007, "JPL Planetary and Lunar Ephemerides: Export Information," (Pasadena, CA: JPL) http://ssd.jpl.nasa.gov/?planet_eph_export.
2. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.

Parameters

jd_tdb [day] Two-element array containing the Julian date, which may be split any way (although the first element is usually the "integer" part, and the second element is the "fractional" part). Julian date is on the TDB or "T_eph" time scale. body Major planet number (or that for Sun, Moon, SSB...) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1), or 2 for Earth geocenter – relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else an error code of solarsystem().

See also

planet_eph_manager_hp()

planet_ephem_provider()

ephem_open()

set_planet_provider()

solarsystem()

Since

1.0

References planet_eph_manager_hp().

Provides an interface between the JPL direct-access solar system ephemerides and NOVAS-C for highest precision applications.

This function and planet_eph_manager() were designed to work with the 1997 version of the JPL ephemerides, as noted in the references.

The user must create the binary ephemeris files using software from JPL, and open the file using function ephem_open(), prior to calling this function.

REFERENCES:

1. JPL. 2007, "JPL Planetary and Lunar Ephemerides: Export Information," (Pasadena, CA: JPL) http://ssd.jpl.nasa.gov/?planet_eph_export.
2. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.

Parameters

jd_tdb [day] Two-element array containing the Julian date, which may be split any way (although the first element is usually the "integer" part, and the second element is the "fractional" part). Julian date is on the TDB or "T_eph" time scale. body Major planet number (or that for Sun, Moon, SSB...) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1), or 2 for Earth geocenter – relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else 1 if the 'body' is invalid, or 2 if the 'origin' is invalid, or 3 if there was an error providing ephemeris data.

See also

planet_eph_manager

planet_ephem_provider_hp()

ephem_open()

set_planet_provider_hp()

Since

1.0

References NOVAS_BARYCENTER, NOVAS_HELIOCENTER, NOVAS_MOON, NOVAS_PLANETS, NOVAS_SUN, and planet_ephemeris().

Major planet ephemeris data via the same generic ephemeris provider that is configured by set_ephem_provider() prior to calling this routine. This is the regular (reduced) precision version.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date. body Major planet number (or that for Sun, Moon, SSB...) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else an error code of solarsystem().

See also

planet_ephem_provider_hp()

set_ephem_provider()

solarsystem()

Since

1.0

Author

Attila Kovacs

References planet_ephem_provider_hp().

Major planet ephemeris data via the same generic ephemeris provider that is configured by set_ephem_provider() prior to calling this routine. This is the highest precision version.

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date, split into high and low order components (e.g. integer and fractional parts) for high-precision calculations. body Major planet number (or that for Sun, Moon, SSB...) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else an error code of solarsystem_hp().

See also

planet_ephem_provider()

set_ephem_provider()

solarsystem_hp()

Since

1.0

Author

Attila Kovacs

References get_ephem_provider(), NOVAS_BARYCENTER, NOVAS_HELIOCENTER, NOVAS_PLANET_NAMES_INIT, NOVAS_PLANETS, NOVAS_SSB, and NOVAS_SUN.

Obtains planet positions via the JPL direct-access solar system ephemerides, wtih normal (reduced) precision – typically good to the milliarcsecond level.

It generalizes access to the JPL software by calling a Fortran interface subroutine, 'jplint', instead of making a direct call to the JPL subroutine 'pleph', whose arguments have changed several times throughout the years. This way, any future change to the arguments can be accommodated in 'jplint' rather than in this function.

For supporting JPL ephemerides more generally, including for satellites, asteroids, and comets, you are probably better off using planet_ephem_provider(), and provide an interface, e.g. to the CSPICE library, via novas_ephem_provider instead, which you can then activate dynamically with set_planet_provider().

REFERENCES:

1. JPL. 2007, JPL Planetary and Lunar Ephemerides: Export Information, (Pasadena, CA: JPL) http://ssd.jpl.nasa.gov/?planet_eph_export.
2. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.

Parameters

jd_tdb [day] Two-element array containing the Julian date, which may be split any way (although the first element is usually the "integer" part, and the second element is the "fractional" part). Julian date is on the TDB or "T_eph" time scale. body Major planet number (or that for Sun, Moon, SSB..) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1), or 2 for Earth geocenter – relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else 1 if the 'body' or 'origin' argument is invalid, or else 2 if the 'jplint_()' call failed.

See also

planet_jplint_hp()

planet_ephem_provider()

set_planet_provider()

solarsystem()

Since

1.0

References jplint_(), NOVAS_BARYCENTER, NOVAS_HELIOCENTER, NOVAS_MERCURY, NOVAS_MOON, and NOVAS_SUN.

Obtains planet positions via the JPL direct-access solar system ephemerides, wtih high precision – typically good to below the microarcsecond level.

It generalizes access to the JPL software by calling a Fortran interface subroutine, 'jplint', instead of making a direct call to the JPL subroutine 'pleph', whose arguments have changed several times throughout the years. This way, any future change to the arguments can be accommodated in 'jplint' rather than in this function.

For supporting JPL ephemerides more generally, including for satellites, asteroids, and comets, you are probably better off using planet_ephem_provider(), and provide an interface, e.g. to the CSPICE library, via novas_ephem_provider instead, which you can then activate dynamically with set_planet_provider().

REFERENCES:

1. JPL. 2007, JPL Planetary and Lunar Ephemerides: Export Information, (Pasadena, CA: JPL) http://ssd.jpl.nasa.gov/?planet_eph_export.
2. Kaplan, G. H. "NOVAS: Naval Observatory Vector Astrometry Subroutines"; USNO internal document dated 20 Oct 1988; revised 15 Mar 1990.

Parameters

jd_tdb [day] Two-element array containing the Julian date, which may be split any way (although the first element is usually the "integer" part, and the second element is the "fractional" part). Julian date is on the TDB or "T_eph" time scale. body Major planet number (or that for Sun, Moon, SSB...) origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1), or 2 for Earth geocenter – relative to which to report positions and velocities. [out] position [AU] Position vector of 'body' at jd_tdb; equatorial rectangular coordinates in AU referred to the ICRS. [out] velocity [AU/day] Velocity vector of 'body' at jd_tdb; equatorial rectangular system referred to the ICRS, in AU/day.

Returns

0 if successful, or else an error code of solarsystem().

See also

planet_jplint()

planet_ephem_provider_hp()

set_planet_provider_hp()

solarsystem_hp()

Since

1.0

References jplihp_(), NOVAS_BARYCENTER, NOVAS_HELIOCENTER, NOVAS_MERCURY, NOVAS_MOON, and NOVAS_SUN.

Provides a default ephemeris implementation to handle position and velocity calculations for minor planets, which are not handled by the solarsystem() type calls. The library does not provide a default implementation, but users can provide their own, either as a default statically compiled readeph() implementation, or else a dynamically defined one via ephemeris_set_reader().

You can set the built-in implementation for the library at build time by setting the DEFAULT_READEPH variable in the config.mk.

Deprecated:

This old ephemeris reader is prone to memory leaks, and lacks some useful functionality. Users are strongly encouraged to use the new novas_ephem_provider instead, which can provide dynamically configured implementations at runtime.

Parameters

mp The ID number of the solar-system body for which the position are desired. An actual implementation might use this and/or the name to identify the object. name The name of the solar-system body (usually upper-case). An actual implementation might use this and/or mp to identify the object. jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date for which to find the position and velocity. [out] error Pointer to integer to populate with the error status: 0 if successful, -1 if any of the pointer arguments are NULL, or some non-zero value if the was an error s.t. the position and velocity vector should not be used.

Returns

[AU, AU/day] A newly allocated 6-vector in rectangular equatorial coordinates, containing the heliocentric position coordinates in AU, followed by hte heliocentric velocity components in AU/day. The caller is responsible for calling free() on the returned value when it is no longer needed.

Deprecated:

(legacy function) Use set_ephem_provider() instead to specify what function should be used to calculate ephemeris positions for Solar-system objects. This prototype is provided to extend support for legacy NOVAS C applications only. In NOVAS, the function had to be user defined, as a custom implementation.

See also

set_ephem_provider()

novas_ephem_provider

ephemeris()

NOVAS_EPHEM_OBJECT

A default implementation for regular (reduced) precision handling of major planets, Sun, Moon and the Solar-system barycenter. See DEFAULT_SOLSYS in Makefile to choose the implementation that is built into with the library as a default. Applications can define their own preferred implementations at runtime via set_planet_provider().

Since this is a function that may be provided by existing custom user implementations, we keep the original argument types for compatibility, hence 'short' instead of the more informative enums).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date body Major planet number (or that for the Sun, Moon, or an appropriate barycenter), as defined by enum novas_planet, e.g. NOVAS_MARS (4), NOVAS_SUN (10) or NOVAS_SSB (0). (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS), 1 if the input Julian date ('tjd') is out of range, 2 if 'body' is invalid, or 3 if the ephemeris data cannot be produced for other reasons.

Deprecated:

(legacy function) Use set_planet_provider() instead to specify what function should be used to calculate ephemeris positions for major planets. This function is provided to extend support for legacy NOVAS C applications only. In NOVAS, the function had to be user defined, either by linking against a solsys[1-3].c module, or by providing a custom user implementation.

See also

novas_planet

solarsystem_hp()

set_planet_provider()

place()

ephemeris()

References planet_eph_manager(), and planet_jplint().

A default implementation for high precision handling of major planets, Sun, Moon and the Solar-system barycenter (and other barycenters). See DEFAULT_SOLSYS in Makefile to choose the implementation that is built into the library as a default. Applications can define their own preferred implementations at runtime via set_planet_provider_hp().

Since this is a function that may be provided by existing custom user implementations, we keep the original argument types for compatibility, hence 'short' instead of the more informative enums).

Parameters

jd_tdb [day] Barycentric Dynamical Time (TDB) based Julian date, broken into high and low order components, respectively. Typically, as the integer and fractional parts for the highest precision. body Major planet number (or that for the Sun, Moon, or an appropriate barycenter), as defined by enum novas_planet, e.g. NOVAS_MARS (4), NOVAS_SUN (10) or NOVAS_SSB (0). (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). origin NOVAS_BARYCENTER (0) or NOVAS_HELIOCENTER (1) relative to which to return positions and velocities. (For compatibility with existing NOVAS C compatible user implementations, we keep the original NOVAS C argument type here). [out] position [AU] Position vector of 'body' at 'tjd'; equatorial rectangular coordinates in AU referred to the mean equator and equinox of J2000.0. [out] velocity [AU/day] Velocity vector of 'body' at 'tjd'; equatorial rectangular system referred to the mean equator and equinox of J2000.0, in AU/Day.

Returns

0 if successful, -1 if there is a required function is not provided (errno set to ENOSYS), or some other error code (NOVAS C was not very consistent here...)

Deprecated:

(legacy function) Use set_planet_provider_hp() instead to specify what function should be used to calculate high-precision ephemeris positions for major planets. This function is provided to extend support for legacy NOVAS C applications only. In NOVAS, the function had to be user defined, either by linking against a solsys[1-3].c module, or by providing a custom user implementation.

See also

solarsystem()

set_planet_provider_hp()

place()

ephemeris()

References planet_eph_manager_hp(), and planet_jplint_hp().

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