[daip] Re: 90 station limit

[Eric Greisen]

Sheperd Doeleman writes:

 > I'm trying to do some simulation of arrays with large numbers
 > of antennas partially within AIPS.  Some tasks such as DTSIM
 > and IMAGR accept antenna numbers in excess of 90 but others
 > do not (INDXR for example).  I'd like to use UVMOD to add
 > noise to some simulated uv data sets but this task requires a
 > single source uv file which INDXR refuses to make for files
 > with more than 90 antennas.

          Why are you hung up on INDXR?  For simulations you do not
need calibration.  INDXR prepares an NX table to locate scan
boundaries in a multi-source (i.e. yet to be calibrated) file.

 > 
 > Is it an easy fix to allow INDXR to accept larger N arrays?
 > Would UVMOD work on a SPLIT file with, let's say, 400
 > antennas?

     That - however - is another problem.  The baseline number in AIPS
is stored in a floating point value:

           BL = 256. * IA1 + IA2 + subarray /100.0

So antenna numbers may not exceed 255,  There is nothing of course to
stop you from multiple subarrays (e.g. DBCON) or from lying about
things in this parameter.  IMAGR looks only at u,v - it does not even
examine the antenna numbers.

Eric