SkyOffsetFrame¶
-
class
astropy.coordinates.
SkyOffsetFrame
(*args, **kwargs)[source] [edit on github]¶ Bases:
astropy.coordinates.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 oforigin
.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 theorigin
frame. E.g., iforigin
isICRS
, this object’slat
will be pointed in the direction of Dec, whilelon
will point in the direction of RA.For more on skyoffset frames, see “Sky Offset” Frames.
Parameters: - representation :
BaseRepresentation
or None A representation object or None to have no data (or use the other keywords)
- origin :
SkyCoord
or low-level coordinate object. 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 thisSkyOffsetFrame
.- rotation :
Angle
orQuantity
with angle units 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 classSkyOffsetFrame
. Instead, distinct classes are created on-the-fly for whatever the frame class is oforigin
.Attributes Summary
default_differential
default_representation
frame_attributes
frame_specific_representation_info
name
origin
rotation
Attributes Documentation
-
default_differential
¶
-
default_representation
¶
-
frame_attributes
= {'origin': <astropy.coordinates.attributes.CoordinateAttribute object>, 'rotation': <astropy.coordinates.attributes.QuantityAttribute object>}¶
-
frame_specific_representation_info
¶
-
name
= 'skyoffsetframe'¶
-
origin
= None¶
-
rotation
= <Quantity 0. deg>¶
- representation :