ICRS¶
-
class
astropy.coordinates.
ICRS
(*args, copy=True, representation_type=None, differential_type=None, **kwargs)[source]¶ Bases:
astropy.coordinates.BaseRADecFrame
A coordinate or frame in the ICRS system.
If you’re looking for “J2000” coordinates, and aren’t sure if you want to use this or
FK5
, you probably want to use ICRS. It’s more well-defined as a catalog coordinate and is an inertial system, and is very close (within tens of milliarcseconds) to J2000 equatorial.For more background on the ICRS and related coordinate transformations, see the references provided in the See Also section of the documentation.
Parameters: data :
BaseRepresentation
subclass instanceA representation object or
None
to have no data (or use the coordinate component arguments, see below).ra :
Angle
, optional, must be keywordThe RA for this object (
dec
must also be given andrepresentation
must be None).dec :
Angle
, optional, must be keywordThe Declination for this object (
ra
must also be given andrepresentation
must be None).distance :
Quantity
, optional, must be keywordThe Distance for this object along the line-of-sight. (
representation
must be None).pm_ra_cosdec :
Quantity
, optional, must be keywordThe 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 keywordThe proper motion in Declination for this object (
pm_ra_cosdec
must also be given).radial_velocity :
Quantity
, optional, must be keywordThe radial velocity of this object.
representation_type :
BaseRepresentation
subclass, str, optionalA 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, optionalA 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.Attributes Summary
default_differential
default_representation
frame_specific_representation_info
name
Attributes Documentation
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default_differential
¶
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default_representation
¶
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frame_specific_representation_info
¶
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name
= 'icrs'¶
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