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SunPy

get_horizons_coord#

sunpy.coordinates.get_horizons_coord(body, time='now', id_type=None, *, include_velocity=False)[source]#

Queries JPL HORIZONS and returns a SkyCoord for the location of a solar-system body at a specified time. This location is the instantaneous or “true” location, and is not corrected for light travel time or observer motion.

Note

This function requires the Astroquery package to be installed and requires an Internet connection.

Parameters:

  • body (str) – The solar-system body for which to calculate positions. One can also use the search form linked below to find valid names or ID numbers.

  • id_type (None, str) – See the astroquery documentation for information on id_types: astroquery.jplhorizons. If the installed astroquery version is less than 0.4.4, defaults to 'majorbody'.

  • time (tuple, list, str, pandas.Timestamp, pandas.Series, pandas.DatetimeIndex, datetime.datetime, datetime.date, numpy.datetime64, numpy.ndarray, astropy.time.Time, dict) – Time to use in a parse_time-compatible format.

    Alternatively, this can be a dictionary defining a range of times and dates; the range dictionary has to be of the form {‘start’: start_time, ‘stop’: stop_time, ‘step’:’n[y|d|m|s]’}. start_time and stop_time must be in a parse_time-compatible format, and are interpreted as UTC time. step must be a string with either a number and interval length (e.g. for every 10 seconds, '10s'), or a plain number for a number of evenly spaced intervals. For more information see the docstring of astroquery.jplhorizons.HorizonsClass.

  • include_velocity (bool, optional) – If True, include the body’s velocity in the output coordinate. Defaults to False.

Returns:

SkyCoord – Location of the solar-system body

Notes

Be aware that there can be discrepancies between the coordinates returned by JPL HORIZONS, the coordinates reported in mission data files, and the coordinates returned by get_body_heliographic_stonyhurst.

References

Examples

>>> from sunpy.coordinates.ephemeris import get_horizons_coord

Query the location of Venus

>>> get_horizons_coord('Venus barycenter', '2001-02-03 04:05:06')  
INFO: Obtained JPL HORIZONS location for Venus Barycenter (2) [sunpy.coordinates.ephemeris]
<SkyCoord (HeliographicStonyhurst: obstime=2001-02-03T04:05:06.000, rsun=695700.0 km): (lon, lat, radius) in (deg, deg, AU)
    (-33.93155836, -1.64998443, 0.71915147)>

Query the location of the SDO spacecraft

>>> get_horizons_coord('SDO', '2011-11-11 11:11:11')  
INFO: Obtained JPL HORIZONS location for Solar Dynamics Observatory (spac [sunpy.coordinates.ephemeris]
<SkyCoord (HeliographicStonyhurst: obstime=2011-11-11T11:11:11.000, rsun=695700.0 km): (lon, lat, radius) in (deg, deg, AU)
    (0.01019118, 3.29640728, 0.99011042)>

Query the location of the SOHO spacecraft via its ID number (-21)

>>> get_horizons_coord(-21, '2004-05-06 11:22:33')  
INFO: Obtained JPL HORIZONS location for SOHO (spacecraft) (-21) [sunpy.coordinates.ephemeris]
<SkyCoord (HeliographicStonyhurst: obstime=2004-05-06T11:22:33.000, rsun=695700.0 km): (lon, lat, radius) in (deg, deg, AU)
    (0.25234902, -3.55863633, 0.99923086)>

Query the location and velocity of the asteroid Juno

>>> get_horizons_coord('Juno', '1995-07-18 07:17', 'smallbody', include_velocity=True)  
INFO: Obtained JPL HORIZONS location for 3 Juno (A804 RA) [sunpy.coordinates.ephemeris]
<SkyCoord (HeliographicStonyhurst: obstime=1995-07-18T07:17:00.000, rsun=695700.0 km): (lon, lat, radius) in (deg, deg, AU)
    (-25.16107532, 14.59098438, 3.17667664)
 (d_lon, d_lat, d_radius) in (arcsec / s, arcsec / s, km / s)
    (-0.03306548, 0.00052415, -2.66709222)>

Query the location of Solar Orbiter at a set of 12 regularly sampled times

>>> get_horizons_coord('Solar Orbiter',
...                    time={'start': '2020-12-01',
...                           'stop': '2020-12-02',
...                           'step': '12'})  
INFO: Obtained JPL HORIZONS location for Solar Orbiter (spacecraft) (-144 [sunpy.coordinates.ephemeris]
...
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