GCRS¶
-
class
astropy.coordinates.
GCRS
(*args, **kwargs)[source] [edit on github]¶ Bases:
astropy.coordinates.BaseCoordinateFrame
A coordinate or frame in the Geocentric Celestial Reference System (GCRS).
GCRS is distinct form ICRS mainly in that it is relative to the Earth’s center-of-mass rather than the solar system Barycenter. That means this frame includes the effects of abberation (unlike ICRS). For more background on the GCRS, see the references provided in the See Also section of the documentation. (Of particular note is Section 1.2 of USNO Circular 179)
This frame also includes frames that are defined relative to the Earth, but that are offset (in both position and velocity) from the Earth.
This frame has these frame attributes:
obstime
The time at which the observation is taken. Used for determining the position of the Earth.
obsgeoloc
3-vector giving the position of the observer relative to the center-of-mass of the Earth, oriented the same as BCRS/ICRS. Defaults to 0, meaning “true” GCRS.
obsgeovel
3-vector giving the velocity of the observer relative to the center-of-mass of the Earth, oriented the same as BCRS/ICRS. Defaults to 0, meaning “true” GCRS.
Parameters: representation :
BaseRepresentation
or NoneA representation object or None to have no data (or use the other keywords)
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).Attributes Summary
default_representation
frame_attributes
frame_specific_representation_info
name
obsgeoloc
obsgeovel
obstime
Attributes Documentation
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default_representation
¶
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frame_attributes
= OrderedDict([('obstime', <astropy.coordinates.baseframe.TimeFrameAttribute object at 0x7ff5256c6fd0>), ('obsgeoloc', <astropy.coordinates.baseframe.QuantityFrameAttribute object at 0x7ff5256fe050>), ('obsgeovel', <astropy.coordinates.baseframe.QuantityFrameAttribute object at 0x7ff5256fe0d0>)])¶
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frame_specific_representation_info
¶
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name
= 'gcrs'¶
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obsgeoloc
= <Quantity [ 0., 0., 0.] m>¶
-
obsgeovel
= <Quantity [ 0., 0., 0.] m / s>¶
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obstime
= <Time object: scale='utc' format='jyear_str' value=J2000.000>¶