[daip] LTESS question

[Eric Greisen]

Lawrence Rudnick writes:

 >    Info:  we've been delayed by vacation of sysadmin, but hope to MNJ in 
 > next couple of days.  In meantime, I want to clarify a couple things.   
 > I have been successful, and was successful with a new dataset this 
 > morning (using not-updated 31DEC06) with running FLATN with pbparm 0.  
 > This time I was using 1378 maps in RA-TAN projection, imsize 191, and 
 > creating FLATN image 2048x2048.  So FLATN seems to work with some 
 > datasets and not with others.  
 >    Question:  are the fixes and tests you've done sufficient to explain 
 > why I got failures on my NVSS dataset of 2326 fields?
 >    Question:  can I continue to use PBPARM 0? other critical input 
 > parameters?
 > 

If all of PBPARM is zero then it tells the task to use the VLA beam
(or ATCA) centered on the pointing position in the header of each
image.  If they really are a mosaic, then this is what you want.  The
NVSS ones do not want a primary beam correction.  The problem came
from PBPARM = 0.05, 1, 0, 0, 0, 0, 0.  This attempts to say do do no
primary beam correction - unfortunately the low level beam correction
routine was too "smart" and said that 0 for the beam shape cannot be
right and so substituted the VLA.  I have changed FLATN to recognize
PBPARM = x, y, 0 wioth x and y > 0 as code for "do mosaicing with no
primary beam correction".

Eric