[alma-config]multiplication of synthesized beam by primary beam in optimization

[John Conway]

I just sent this, the original was cought up in the moderator 
because of the attachemnt, here is the text only.



> 
> 
> all,
> 
> keep in mind that leonia has *never* been arguing about the
> mosaicing case - only the *single-field* case.  he has been
> trying, unsuccessfully, to make this point for 6 months.
> 
> if we say simply that the compact configuration will do mostly
> mosaicing (although i suspect it will be less than the
> 86.3% number that mark puts forward, i think it is safe to
> say that it will spend a majority of time mosaicing), then
> the argument is non-existent, since mark has shown (and dave
> has reproduced/verified) that in that case you multiply by
> the PB*PB.  so, for the compact configuration, this is the
> thing to do.
> 
> i defer to dave & mark on this - they understand it better than i do.
> 
> i would like to see john's comments on this topic though.
> 
> 
> 	-bryan
>

Hi,

 I havn't been following all the arguments in detail. For the most compact  
array I have been assuming multiplcation by PB*PB - realising 
from Mark and Stephane this was the concensus for mosaicing. With this
I can get down to  peak sidelobes around 2.2% anywahere within this beam
by beam optimisation. As an attachment is the present design for the most 
compact array. Max Kraus is looking at the transporter access issues and
it looks OK. This design has the ame resolution as Leonia's two 
road design, but the distances and turns for the transporter are smaller.
The ring-like near in sidelobes present in the two ring design are
eliminated by this triangular design, it is also good for interfacing 
with the smallest spiral and for using to popolaute to get short spacings
for teh larger arrays. The row of pads to the S is used in the N-S
extended arrays, these pads have yet to be optimised.

For the larger confgurations I am optimising on uv coverage first
with a final run through on beam optimisation. For these the far sidelobe
pattern is effected by the  z component of the baselines (there are
difference of  hundreds of meteres  in altitude between our antennas
remember, we are not  on a perfect plane!) for anything
other than snapshots at the zenith them it turns out not worth worth 
optimising mor than 20-30 beam out anyway - the augument then about
whether to use PB or PB*PB for these larger arrays is then 
totally academic.
 
I am off on vacation tomorrow  for three weeks and return August 1st.

In the last 3 weeks I have made a lot of progress on masks, compact
configuration and the  array out to 4km baseline (I can do this with 170
pads including 6  which are only used in the N-S exntened compact arrays,
I will maybe add a few more when I get back). I expect another 
full weeks work after I come back and I will have a fairly complete design
available  for <4km which I will post on the web and be interested 
in feedback from the configuraton group.

 Yours
   John