[daip] Error running SDVEL

[Eric Greisen]

Jeff Mangum wrote:
> I have tried multiple combinations of DPARM all of which produce 
> incorrectly-velocity-shifted maps.  At this point I suspect that this 
> particular collection of data is the problem, not SDVEL.  I really do 
> not want to fiddle with this any more.  How can I manually shift the 
> velocity axes to make the image fields line-up?  Thanks.

The short answer is that you can't.  The longer answer depends on what 
the telescope did.  I am about to go off on a vacation and am working on 
a pressing matter affecting a lot of VLA observing time.  I do not have 
time to look at this now.

The issue is - in one OTF field, the telescope may or may not have 
changed frequency while observing.  But each position will have a 
spectrum with a different velocity than its neighbor for a particular 
channel all within the same field.  So it is wrong to label the cube in 
velocity - but with many of the modes that the 12m used, it is also 
wrong to label it with frequency since it did change frequency some at 
points within the observation.  So I dod not know what to do with this.

Note - in about 2 weeks I might have time to really look at this.  But 
not until at least then.

Eric