[daip] AIPS limitations for large numbers of antennas

[Lynn Matthews]

I'm gearing up to do some experiments using simulated u-v data sets, some 
of which might include up to a few hundred stations. In anticipation 
of this, I've been trying to better understand what the limitations of 
AIPS would be for imaging and otherwise manipulating these kinds of data.
In short, is there hope that this could work?

In some experiments I've done so far, I find that, e.g., IMAGR seems happy 
imaging a u-v data set with 500 stations---until the end when it prints a 
series of messages of the type:

IMAGR2 15:26:35 GETANT: STATION NUMBER    91 FOR ENTRY=  91 SUBA=  1

for all stations with ant # >90. What are the actual repercussions of 
this? Is this N=90 limit one that could be modified?

Obviously the arrays ANTENNAS and BASELINE allow a maximum of 50 elements, 
but in some other tests I seem to be encountering some problems even 
staying within those limits. For example, if I take a large-N u-v data set 
and attempt to extract a subset of the antennas using UVCOP, I find that 
if I try to extract, say 35 antennas & baselines, not all of the 
visibilities are copied. For N~40, there is a series of messages of the 
type:

UVCOP2: ZCLOSE: LUN = 39 ALREADY CLOSED IN FTAB ON SEARCH

and for N=50:

ZMSGCL: LUN =  6 ALREADY CLOSED IN FTAB ON SEARCH
ZTTYIO: LUN =            6  NOT OPEN IN FTAB

after which the program hangs for a while and loses an even larger 
fraction of the visibilities. Is this due to some additional constraint on 
the total number of baselines allowed?

Thanks,

Lynn Matthews