EarthLocation¶

class
astropy.coordinates.
EarthLocation
[source] [edit on github]¶ Bases:
astropy.units.quantity.Quantity
Location on the Earth.
Initialization is first attempted assuming geocentric (x, y, z) coordinates are given; if that fails, another attempt is made assuming geodetic coordinates (longitude, latitude, height above a reference ellipsoid). When using the geodetic forms, Longitudes are measured increasing to the east, so west longitudes are negative. Internally, the coordinates are stored as geocentric.
To ensure a specific type of coordinates is used, use the corresponding class methods (
from_geocentric
andfrom_geodetic
) or initialize the arguments with names (x
,y
,z
for geocentric;lon
,lat
,height
for geodetic). See the class methods for details.Notes
This class fits into the coordinates transformation framework in that it encodes a position on the
ITRS
frame. To get a properITRS
object from this object, use theitrs
property.Attributes Summary
ellipsoid
The default ellipsoid used to convert to geodetic coordinates. geocentric
Convert to a tuple with X, Y, and Z as quantities geodetic
Convert to geodetic coordinates for the default ellipsoid. height
Height of the location, for the default ellipsoid. itrs
An ITRS
object with for the location of this object at the defaultobstime
.latitude
Latitude of the location, for the default ellipsoid. longitude
Longitude of the location, for the default ellipsoid. x
The X component of the geocentric coordinates. y
The Y component of the geocentric coordinates. z
The Z component of the geocentric coordinates. Methods Summary
from_geocentric
(x, y, z[, unit])Location on Earth, initialized from geocentric coordinates. from_geodetic
(lon, lat[, height, ellipsoid])Location on Earth, initialized from geodetic coordinates. get_itrs
([obstime])Generates an ITRS
object with the location of this object at the requestedobstime
.get_site_names
()Get list of names of observatories for use with of_site
.of_site
(site_name)Return an object of this class for a known observatory/site by name. to
(unit[, equivalencies])Returns a new Quantity
object with the specified units.to_geocentric
()Convert to a tuple with X, Y, and Z as quantities to_geodetic
([ellipsoid])Convert to geodetic coordinates. Attributes Documentation

ellipsoid
¶ The default ellipsoid used to convert to geodetic coordinates.

geocentric
¶ Convert to a tuple with X, Y, and Z as quantities

geodetic
¶ Convert to geodetic coordinates for the default ellipsoid.

height
¶ Height of the location, for the default ellipsoid.

latitude
¶ Latitude of the location, for the default ellipsoid.

longitude
¶ Longitude of the location, for the default ellipsoid.

x
¶ The X component of the geocentric coordinates.

y
¶ The Y component of the geocentric coordinates.

z
¶ The Z component of the geocentric coordinates.
Methods Documentation

classmethod
from_geocentric
(x, y, z, unit=None)[source] [edit on github]¶ Location on Earth, initialized from geocentric coordinates.
Parameters: x, y, z :
Quantity
or arraylikeCartesian coordinates. If not quantities,
unit
should be given.unit :
UnitBase
object or NonePhysical unit of the coordinate values. If
x
,y
, and/orz
are quantities, they will be converted to this unit.Raises: astropy.units.UnitsError
If the units on
x
,y
, andz
do not match or an invalid unit is given.ValueError
If the shapes of
x
,y
, andz
do not match.TypeError
If
x
is not aQuantity
and no unit is given.

classmethod
from_geodetic
(lon, lat, height=0.0, ellipsoid=None)[source] [edit on github]¶ Location on Earth, initialized from geodetic coordinates.
Parameters: lon :
Longitude
or floatEarth East longitude. Can be anything that initialises an
Angle
object (if float, in degrees).lat :
Latitude
or floatEarth latitude. Can be anything that initialises an
Latitude
object (if float, in degrees).height :
Quantity
or float, optionalHeight above reference ellipsoid (if float, in meters; default: 0).
ellipsoid : str, optional
Name of the reference ellipsoid to use (default: ‘WGS84’). Available ellipsoids are: ‘WGS84’, ‘GRS80’, ‘WGS72’.
Raises: astropy.units.UnitsError
If the units on
lon
andlat
are inconsistent with angular ones, or that onheight
with a length.ValueError
If
lon
,lat
, andheight
do not have the same shape, or ifellipsoid
is not recognized as among the ones implemented.Notes
For the conversion to geocentric coordinates, the ERFA routine
gd2gc
is used. See https://github.com/liberfa/erfa

get_itrs
(obstime=None)[source] [edit on github]¶ Generates an
ITRS
object with the location of this object at the requestedobstime
.Parameters: obstime :
Time
or NoneThe
obstime
to apply to the newITRS
, or if None, the defaultobstime
will be used.Returns: itrs :
ITRS
The new object in the ITRS frame

classmethod
get_site_names
()[source] [edit on github]¶ Get list of names of observatories for use with
of_site
.Note
When this function is called, it will first attempt to download site information from the astropy data server. If it cannot (i.e., an internet connection is not available), it will fall back on the list included with astropy (which is a limited and dated set of sites). If you think a site should be added, issue a pull request to the astropydata repository .
Returns: names : list of str
List of valid observatory names
See also
of_site
 Gets the actual location object for one of the sites names this returns.

classmethod
of_site
(site_name)[source] [edit on github]¶ Return an object of this class for a known observatory/site by name.
This is intended as a quick convenience function to get basic site information, not a fullyfeatured exhaustive registry of observatories and all their properties.
Note
When this function is called, it will attempt to download site information from the astropy data server. If you would like a site to be added, issue a pull request to the astropydata repository . If a site cannot be found in the registry (i.e., an internet connection is not available), it will fall back on a builtin list, In the future, this bundled list might include a versioncontrolled list of canonical observatories extracted from the online version, but it currently only contains the Greenwich Royal Observatory as an example case.
Parameters: site_name : str
Name of the observatory (caseinsensitive).
Returns: site : This class (a
EarthLocation
or subclass)The location of the observatory.
See also
get_site_names
 the list of sites that this function can access

to
(unit, equivalencies=[])[source] [edit on github]¶ Returns a new
Quantity
object with the specified units.Parameters: unit :
UnitBase
instance, strequivalencies : list of equivalence pairs, optional
A list of equivalence pairs to try if the units are not directly convertible. See Equivalencies. If not provided or
[]
, class default equivalencies will be used (none forQuantity
, but may be set for subclasses) IfNone
, no equivalencies will be applied at all, not even any set globally or within a context.

to_geocentric
()[source] [edit on github]¶ Convert to a tuple with X, Y, and Z as quantities

to_geodetic
(ellipsoid=None)[source] [edit on github]¶ Convert to geodetic coordinates.
Parameters: ellipsoid : str, optional
Reference ellipsoid to use. Default is the one the coordinates were initialized with. Available are: ‘WGS84’, ‘GRS80’, ‘WGS72’
Returns: (lon, lat, height) : tuple
Raises: ValueError
if
ellipsoid
is not recognized as among the ones implemented.Notes
For the conversion to geodetic coordinates, the ERFA routine
gc2gd
is used. See https://github.com/liberfa/erfa
