./toolbox
velocity_axis.pro

Last modification date:

Wed Sep 28 13:27:11 2016

VELOCITY_AXIS

function VELOCITY_AXIS(data, [veldef=string], [frame=string], [true_frame=variable], [true_veldef=variable])

Construct a velocity axis from a data structure.

Returns

A vector of velocities (m/s). May also set the keywords. Returns -1 on a severe error. If the veldef or ref_frame are invalid this will use the values found in the data structure and the values of the true_veldef and true_frame keywords will be set.

Uses

chantovel

Version

$Id$

Parameters
data in, required spectrum	The data structure to use in constructing a velocity axis.

Keywords
veldef in, optional string	The velocity definition to use, chosen from 'RADIO', 'OPTICAL', and 'TRUE'. If not supplied, the data.velocity_definition value will be used.
frame in, optional string	The reference frame to use. If not supplied, the data.velocity_definition value will be used. See frame_velocity for a full list of supported reference frames.
true_frame out, optional variable	The actual rest frame used in constructing the velocity axis. The only way this will not equal the frame argument is if that argument was invalid. In that case, this keyword will be the same as the frame in data.velocity_definition.
true_veldef out, optional variable	The actual velocity frame used in constructing the velocity axis. The only way this will not equal the frame argument is if that argument was invalid. In that case, this keyword will be the same as data.velocity_definition.