[daip] Re: aips bug

[Eric Greisen]

Gary Welch writes:
 > Eric,
 > 
 > I've discovered a bug in the imhead verb.  With the appropriate toggle of 
 > altsw, I expect to see the velocity of the central spctral channel reported.  
 > The reported value is incorrect.  Toggling to frequency, however, appears to 
 > result in the correct frequency being reported for the same channel.
 > 
 > I realize that you'd like copies of various things to better define the 
 > problem. Unfortunately, my aips skills are not yet up to the task of 
 > providing them with this message.
 > 
 > Gary
 > 
I suspect that the wrong parameters are in the header.  IMHEAD is a
very simple minded routine that reports solely what is there.  ALTSW
does more complex things but it works so far as I know just fine.  I
suspect erroneous velocity data - or worse an observation made at a
velocity other than the one you wanted.  Where does the velocity
information come from - FILLM or FITLD or did you have to insert it?
A full IMHEADER in both positions of the axis would help...

Eric