Bases: BaseCoordinateFrame
A frame which is relative to some specific position and oriented to match its frame.
SkyOffsetFrames always have component names for spherical coordinates of lon
/lat
, not the component names for the frame of origin
.
This is useful for calculating offsets and dithers in the frame of the sky relative to an arbitrary position. Coordinates in this frame are both centered on the position specified by the origin
coordinate, and they are oriented in the same manner as the origin
frame. E.g., if origin
is ICRS
, this object’s lat
will be pointed in the direction of Dec, while lon
will point in the direction of RA.
For more on skyoffset frames, see “Sky Offset” Frames.
BaseRepresentation
or None
A representation object or None to have no data (or use the other keywords)
The coordinate which specifies the origin of this frame. Note that this origin is used purely for on-sky location/rotation. It can have a distance
but it will not be used by this SkyOffsetFrame
.
The final rotation of the frame about the origin
. The sign of the rotation is the left-hand rule. That is, an object at a particular position angle in the un-rotated system will be sent to the positive latitude (z) direction in the final frame.
Notes
SkyOffsetFrame
is a factory class. That is, the objects that it yields are not actually objects of class SkyOffsetFrame
. Instead, distinct classes are created on-the-fly for whatever the frame class is of origin
.
Attributes Summary
Methods Summary
Attributes Documentation
Default representation for differential data (e.g., velocity)
Default representation for position data
Mapping for frame-specific component names
The origin of the offset frame
No default value
The rotation angle for the frame orientation
Default: 0.0 deg
Methods Documentation
Ensure the wrap angle for any spherical representations.
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