[alma-config]My point of view

[Leonia Kogan]

Hi,

I want to return back to the comparison of the two(my) and Boone) compact 
configurations.

I had optimized my configuration inside of the circle of radius equaled 
to the two side size of the primary beam at the level zero.

Now David and probably Frederick multiply the PSFs by the Primary beam 
(sqrt of..) to compare the two configuration.
So it is clear that there had not been a sence to optimise (by me) at the 
double size area.

So I want to make the two statements:

1. If I optimise sidelobes inside the less circle (say one or less PB radius)
   the side lobes could be better (I think twice or more). They would be less 
   than 2-3%

2. I do not belive that the PSF with a PB can be described as a multiplication 
   of the original PSF by Primary beam or any other function.

  The following analysis excludes the mosaic because I am not familia with 
  the detail of mosaic

Lets consider the sky with center at the PB center.
Lets PSF maximum points to the direction determined by the vector de 
and a sidelobe of the PSF is determined by the vector eshift.
Then the position of the sidelobe relatively the position of the PSF's 
maximum is 

e = eshift-de

The sky signal coming to the sidelobe will be attenuated by the PB 
at PB(eshift) 

and the signal coming from the direction of the max PSF
be attenuated by the PB at PB(de) 

So the modified PSF (PSFmod) when we clean the component from the direcrion de 
can be described by the following equation:

PSFmod(e) = PSF(e) * PB(e+de) / PB(de)   (1)

So the function we have to use to multiply PSF is not the constant 
function but depend on the position of the clean component relatively 
PB center.

So if we want to compare configurations using the worst side lobe metric we 
need to calculate (eq 1) the worst side lobe inside of the given circle 
for pointing PSF at all components inside of this circle.

Leonia