PrecessedGeocentric¶
-
class
astropy.coordinates.
PrecessedGeocentric
(*args, copy=True, representation_type=None, differential_type=None, **kwargs)[source] [edit on github]¶ Bases:
astropy.coordinates.BaseRADecFrame
A coordinate frame defined in a similar manner as GCRS, but precessed to a requested (mean) equinox. Note that this does not end up the same as regular GCRS even for J2000 equinox, because the GCRS orientation is fixed to that of ICRS, which is not quite the same as the dynamical J2000 orientation.
The frame attributes are listed under Other Parameters
Parameters: - data :
BaseRepresentation
subclass instance A representation object or
None
to have no data (or use the coordinate component arguments, see below).- ra :
Angle
, optional, must be keyword The RA for this object (
dec
must also be given andrepresentation
must be None).- dec :
Angle
, optional, must be keyword The Declination for this object (
ra
must also be given andrepresentation
must be None).- distance :
Quantity
, optional, must be keyword The Distance for this object along the line-of-sight. (
representation
must be None).- pm_ra_cosdec :
Quantity
, optional, must be keyword The proper motion in Right Ascension (including the
cos(dec)
factor) for this object (pm_dec
must also be given).- pm_dec :
Quantity
, optional, must be keyword The proper motion in Declination for this object (
pm_ra_cosdec
must also be given).- radial_velocity :
Quantity
, optional, must be keyword The radial velocity of this object.
- representation_type :
BaseRepresentation
subclass, str, optional A representation class or string name of a representation class. This sets the expected input representation class, thereby changing the expected keyword arguments for the data passed in. For example, passing
representation_type='cartesian'
will make the classes expect position data with cartesian names, i.e.x, y, z
in most cases.- differential_type :
BaseDifferential
subclass, str, dict, optional A differential class or dictionary of differential classes (currently only a velocity differential with key ‘s’ is supported). This sets the expected input differential class, thereby changing the expected keyword arguments of the data passed in. For example, passing
differential_type='cartesian'
will make the classes expect velocity data with the argument namesv_x, v_y, v_z
.- copy : bool, optional
If
True
(default), make copies of the input coordinate arrays. Can only be passed in as a keyword argument.
Other Parameters: - equinox :
Time
The (mean) equinox to precess the coordinates to.
- obstime :
Time
The time at which the observation is taken. Used for determining the position of the Earth.
- obsgeoloc :
CartesianRepresentation
,Quantity
The position of the observer relative to the center-of-mass of the Earth, oriented the same as BCRS/ICRS. Either [0, 0, 0],
CartesianRepresentation
, or proper input for one, i.e., aQuantity
with shape (3, …) and length units. Defaults to [0, 0, 0], meaning “true” Geocentric.- obsgeovel :
CartesianRepresentation
,Quantity
The velocity of the observer relative to the center-of-mass of the Earth, oriented the same as BCRS/ICRS. Either 0,
CartesianRepresentation
, or proper input for one, i.e., aQuantity
with shape (3, …) and velocity units. Defaults to [0, 0, 0], meaning “true” Geocentric.
Attributes Summary
default_differential
default_representation
equinox
frame_attributes
frame_specific_representation_info
name
obsgeoloc
obsgeovel
obstime
Attributes Documentation
-
default_differential
¶
-
default_representation
¶
-
equinox
= <Time object: scale='utc' format='jyear_str' value=J2000.000>¶
-
frame_attributes
= {'equinox': <astropy.coordinates.attributes.TimeAttribute object>, 'obsgeoloc': <astropy.coordinates.attributes.CartesianRepresentationAttribute object>, 'obsgeovel': <astropy.coordinates.attributes.CartesianRepresentationAttribute object>, 'obstime': <astropy.coordinates.attributes.TimeAttribute object>}¶
-
frame_specific_representation_info
¶
-
name
= 'precessedgeocentric'¶
-
obsgeoloc
= <CartesianRepresentation (x, y, z) in m (0., 0., 0.)>¶
-
obsgeovel
= <CartesianRepresentation (x, y, z) in m / s (0., 0., 0.)>¶
-
obstime
= <Time object: scale='utc' format='jyear_str' value=J2000.000>¶
- data :