GalacticLSR#
- class astropy.coordinates.GalacticLSR(*args, copy=True, representation_type=None, differential_type=None, **kwargs)[source]#
Bases:
BaseCoordinateFrame
A coordinate or frame in the Local Standard of Rest (LSR), axis-aligned to the Galactic frame.
This coordinate frame is axis-aligned and co-spatial with
ICRS
, but has a velocity offset relative to the solar system barycenter to remove the peculiar motion of the sun relative to the LSR. Roughly, the LSR is the mean velocity of the stars in the solar neighborhood, but the precise definition of which depends on the study. As defined in Schönrich et al. (2010): “The LSR is the rest frame at the location of the Sun of a star that would be on a circular orbit in the gravitational potential one would obtain by azimuthally averaging away non-axisymmetric features in the actual Galactic potential.” No such orbit truly exists, but it is still a commonly used velocity frame.We use default values from Schönrich et al. (2010) for the barycentric velocity relative to the LSR, which is defined in Galactic (right-handed) cartesian velocity components \((U, V, W) = (11.1, 12.24, 7.25)~{{\rm km}}~{{\rm s}}^{{-1}}\). These values are customizable via the
v_bary
argument which specifies the velocity of the solar system barycenter with respect to the LSR.The frame attributes are listed under Other Parameters.
- Parameters:
- data
BaseRepresentation
subclass instance A representation object or
None
to have no data (or use the coordinate component arguments, see below).- l
Angle
, optional, keyword-only The Galactic longitude for this object (
b
must also be given andrepresentation
must be None).- b
Angle
, optional, keyword-only The Galactic latitude for this object (
l
must also be given andrepresentation
must be None).- distance
Quantity
[:ref: ‘length’], optional, keyword-only The Distance for this object along the line-of-sight. (
representation
must be None).- pm_l_cosb
Quantity
[:ref: ‘angular speed’], optional, keyword-only The proper motion in Galactic longitude (including the
cos(b)
term) for this object (pm_b
must also be given).- pm_b
Quantity
[:ref: ‘angular speed’], optional, keyword-only The proper motion in Galactic latitude for this object (
pm_l_cosb
must also be given).- radial_velocity
Quantity
[:ref: ‘speed’], optional, keyword-only The radial velocity of this object.
- representation_type
BaseRepresentation
subclass,str
, optional A 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 unless overridden viaframe_specific_representation_info
. To see this frame’s names, check out<this frame>().representation_info
.- differential_type
BaseDifferential
subclass,str
,dict
, optional A 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
unless overridden viaframe_specific_representation_info
. To see this frame’s names, check out<this frame>().representation_info
.- copybool, optional
If
True
(default), make copies of the input coordinate arrays. Can only be passed in as a keyword argument.
- data
- Other Parameters:
- v_bary
CartesianDifferential
The velocity of the solar system barycenter with respect to the LSR, in Galactic cartesian velocity components.
- v_bary
Attributes Summary
Default representation for differential data (e.g., velocity)
Default representation for position data
Mapping for frame-specific component names
The relative velocity of the solar-system barycenter
Attributes Documentation
- default_differential#
Default representation for differential data (e.g., velocity)
- default_representation#
Default representation for position data
- frame_attributes = {'v_bary': <astropy.coordinates.attributes.DifferentialAttribute object>}#
- frame_specific_representation_info#
Mapping for frame-specific component names
- name = 'galacticlsr'#
- v_bary#
The relative velocity of the solar-system barycenter
Default: (11.1, 12.24, 7.25) km / s