Uses a velocity map to extract values from a velocity cube forming a new map
While creating velocity maps is the expected usage for the script, it makes no specific tests that the Z co-ordinate is velocity, or even that the image value is velocity. In mathematical form the output image values are given by the following expression.
One application is multi-spectral imaging in complex molecular clouds, where one optically thin spectral line provides a clearer mapping of the cloud and system velocities. Using this specie’s velocity map traces the varying velocity, and thus data observed through different spectral lines can be compared, enabling the calculation of cloud parameters such as opacity.
-mfilename
The name of a two-dimensional velocity map, where the data values are velocities. It should have the
same spatial co-ordinates as the supplied cube. Such a map can be created using velmap or
KAPPA:COLLAPSE with the Iwc or Comax estimators. By default the script will prompt for the input
cube.
-ofilename
The filename for the output NDF velocity map.
The script assumes X and Y axes are spatial and Z is spectral. Use KAPPA:PERMAXES to re-orient the cube if that is not the case.
A further assumption is the cube’s Z-axis co-ordinate matches the data values in the supplied image. If that is not the case, change the co-ordinate system with KAPPA:WCSFRAME and/or KAPPA:WCSATTRIB.
It propagates the original variances from the cube, but does not account for errors in the input velocity map affecting the values extracted from the cube.