PrecessedGeocentric¶
-
class
astropy.coordinates.
PrecessedGeocentric
(*args, copy=True, representation_type=None, differential_type=None, **kwargs)[source]¶ 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 unless overriden viaframe_specific_representation_info
. To see this frame’s names, check out<this frame>().representation_info
.- 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
unless overriden viaframe_specific_representation_info
. To see this frame’s names, check out<this frame>().representation_info
.- copybool, optional
If
True
(default), make copies of the input coordinate arrays. Can only be passed in as a keyword argument.
- data
- 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.
- equinox
Attributes Summary
Attributes Documentation
-
default_differential
¶
-
default_representation
¶
-
equinox
= <Time object: scale='tt' 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='tt' format='jyear_str' value=J2000.000>¶