Orphan¶
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class
gala.coordinates.
Orphan
(*args, **kwargs)[source]¶ Bases:
astropy.coordinates.BaseCoordinateFrame
A Heliocentric spherical coordinate system defined by the orbit of the Orphan stream, as described in Newberg et al. 2010 (see: http://arxiv.org/abs/1001.0576).
For more information about this class, see the Astropy documentation on coordinate frames in
coordinates
.Parameters: representation :
BaseRepresentation
or NoneA representation object or None to have no data (or use the other keywords)
Lambda : angle_like, optional, must be keyword
The longitude-like angle corresponding to Orphan’s orbit.
Beta : angle_like, optional, must be keyword
The latitude-like angle corresponding to Orphan’s orbit.
distance :
Quantity
, optional, must be keywordThe Distance for this object along the line-of-sight.
Attributes Summary
cartesian
Shorthand for a cartesian representation of the coordinates in this object. data
The coordinate data for this object. default_representation
frame_attributes
frame_specific_representation_info
has_data
True if this frame has data
, False otherwise.isscalar
name
representation
The representation of the data in this frame, as a class that is subclassed from BaseRepresentation
.representation_component_names
representation_component_units
representation_info
A dictionary with the information of what attribute names for this frame apply to particular representations. shape
spherical
Shorthand for a spherical representation of the coordinates in this object. Methods Summary
get_frame_attr_names
()is_equivalent_frame
(other)Checks if this object is the same frame as the other
object.is_frame_attr_default
(attrnm)Determine whether or not a frame attribute has its value because it’s the default value, or because this frame was created with that value explicitly requested. is_transformable_to
(new_frame)Determines if this coordinate frame can be transformed to another given frame. realize_frame
(representation)Generates a new frame with new data from another frame (which may or may not have data). represent_as
(new_representation[, ...])Generate and return a new representation of this frame’s data
as a Representation object.separation
(other)Computes on-sky separation between this coordinate and another. separation_3d
(other)Computes three dimensional separation between this coordinate and another. transform_to
(new_frame)Transform this object’s coordinate data to a new frame. Attributes Documentation
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cartesian
¶ Shorthand for a cartesian representation of the coordinates in this object.
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data
¶ The coordinate data for this object. If this frame has no data, an
ValueError
will be raised. Usehas_data
to check if data is present on this frame object.
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default_representation
¶
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frame_attributes
= OrderedDict()¶
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frame_specific_representation_info
¶
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isscalar
¶
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name
= 'orphan'¶
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representation
¶ The representation of the data in this frame, as a class that is subclassed from
BaseRepresentation
. Can also be set using the string name of the representation.
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representation_component_names
¶
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representation_component_units
¶
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representation_info
¶ A dictionary with the information of what attribute names for this frame apply to particular representations.
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shape
¶
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spherical
¶ Shorthand for a spherical representation of the coordinates in this object.
Methods Documentation
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get_frame_attr_names
()¶
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is_equivalent_frame
(other)¶ Checks if this object is the same frame as the
other
object.To be the same frame, two objects must be the same frame class and have the same frame attributes. Note that it does not matter what, if any, data either object has.
Parameters: other : BaseCoordinateFrame
the other frame to check
Returns: isequiv : bool
True if the frames are the same, False if not.
Raises: TypeError
If
other
isn’t aBaseCoordinateFrame
or subclass.
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is_frame_attr_default
(attrnm)¶ Determine whether or not a frame attribute has its value because it’s the default value, or because this frame was created with that value explicitly requested.
Parameters: attrnm : str
The name of the attribute to check.
Returns: isdefault : bool
True if the attribute
attrnm
has its value by default, False if it was specified at creation of this frame.
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is_transformable_to
(new_frame)¶ Determines if this coordinate frame can be transformed to another given frame.
Parameters: new_frame : class or frame object
The proposed frame to transform into.
Returns: transformable : bool or str
Notes
A return value of ‘same’ means the transformation will work, but it will just give back a copy of this object. The intended usage is:
if coord.is_transformable_to(some_unknown_frame): coord2 = coord.transform_to(some_unknown_frame)
This will work even if
some_unknown_frame
turns out to be the same frame class ascoord
. This is intended for cases where the frame is the same regardless of the frame attributes (e.g. ICRS), but be aware that it might also indicate that someone forgot to define the transformation between two objects of the same frame class but with different attributes.
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realize_frame
(representation)¶ Generates a new frame with new data from another frame (which may or may not have data).
Parameters: representation : BaseRepresentation
The representation to use as the data for the new frame.
Returns: frameobj : same as this frame
A new object with the same frame attributes as this one, but with the
representation
as the data.
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represent_as
(new_representation, in_frame_units=False)¶ Generate and return a new representation of this frame’s
data
as a Representation object.Note: In order to make an in-place change of the representation of a Frame or SkyCoord object, set the
representation
attribute of that object to the desired new representation.Parameters: new_representation : subclass of BaseRepresentation or string
The type of representation to generate. May be a class (not an instance), or the string name of the representation class.
in_frame_units : bool
Force the representation units to match the specified units particular to this frame
Returns: newrep : BaseRepresentation-derived object
A new representation object of this frame’s
data
.Raises: AttributeError
If this object had no
data
Examples
>>> from astropy import units as u >>> from astropy.coordinates import SkyCoord, CartesianRepresentation >>> coord = SkyCoord(0*u.deg, 0*u.deg) >>> coord.represent_as(CartesianRepresentation) <CartesianRepresentation (x, y, z) [dimensionless] (1.0, 0.0, 0.0)>
>>> coord.representation = CartesianRepresentation >>> coord <SkyCoord (ICRS): (x, y, z) [dimensionless] (1.0, 0.0, 0.0)>
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separation
(other)¶ Computes on-sky separation between this coordinate and another.
Parameters: other :
BaseCoordinateFrame
The coordinate to get the separation to.
Returns: sep :
Angle
The on-sky separation between this and the
other
coordinate.Notes
The separation is calculated using the Vincenty formula, which is stable at all locations, including poles and antipodes [R2].
[R2] http://en.wikipedia.org/wiki/Great-circle_distance
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separation_3d
(other)¶ Computes three dimensional separation between this coordinate and another.
Parameters: other :
BaseCoordinateFrame
The coordinate system to get the distance to.
Returns: sep :
Distance
The real-space distance between these two coordinates.
Raises: ValueError
If this or the other coordinate do not have distances.
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transform_to
(new_frame)¶ Transform this object’s coordinate data to a new frame.
Parameters: new_frame : class or frame object or SkyCoord object
The frame to transform this coordinate frame into.
Returns: transframe
A new object with the coordinate data represented in the
newframe
system.Raises: ValueError
If there is no possible transformation route.
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