[daip] Smoothing option in IMAGR

[Eric Greisen]

Kazi Rygl wrote:
> Dear Sir/Madam,
> 
> I want to report a problem concerning the SMOOTH option in IMAGR for AIPS 
> versions DEC09 and DEC10. 
> When imaging a spectral line data with the option SMOOTH 1 0 (Hanning 
> smoothing) and inspecting the image cube with ISPEC, I noticed that the 
> smoothing was not correctly applied: the spectral shape remains as if 
> unsmoothed.
> I tried the same operation in the DEC08 version, where the spectral shape 
> was indeed altered by the smoothing.
> 
> Could you help me to overcome this problem?

SMOOTH is a basic parameter of the UV data reading and has not 
deliberately changed in many years.  It should be no different in recent 
versions than 31DEC08.  Look at the history file of the output image and 
see if SMOOTH appears there and what its values are.

Try POSSM with SMOOTH in the various versions to see if SMOOTH fails 
there.  Try running SPLIT or SPLAT with SMOOTH and feeding the result 
into IMAGR with no SMOOTH.  IMAGR does so much to the data after the 
data are read that it is sometimes hard to see what is going on but 
without more to go on I cannot see how it could be failing.  I suppose I 
could try it again.

Note I used SMOOTH=1,0 for a 24000 channel cube last December and it 
worked as intended (we had ringing in the spectra due to channels that 
were too wide).

Eric Greisen