[daip] CVEL problem

[Eric Greisen]

Deidre Hunter wrote:
> Eric,
> 
> The lines are relatively narrow and the spectral resolution high. A 
> typical FWHM of an integrated HI line (over the entire galaxy) might be 
> 40 km/s. Our spectral resolution is 2.6 and 1.3 km/s.

The question is how wide is the line at a given pixel not in the 
integrated spectrum.  If it is 2 channels or less you have a problem.
I just took my galaxy which has a spectral resolution of 5 km/s and ran 
CVEL.  The output gave images subtly different from the input as it 
should (freq was tracked in our case but the CL table containing the 
info about that was not present) but they are quite reasonable.  I also 
tried with Hanning and the results were nearly identical.  The 
difference of the 2 CVEL output images was quite weak but showed real 
differences in the uv plane.  I do not find anything wrong, but in my 
case CVEL did not print the shift values, presumably because they were 
quite small.

Eric Greisen