[daip] UNCON and IMAGR
egreisen at nrao.edu
Mon Jun 15 11:26:58 EDT 2009
Hans-Rainer Kloeckner wrote:
> Dear Eric,
> once agin I'm sorry for bothering you.
> We are trying to run a SKA simulation that will contain several
> thousands (~3000-5000) of antennas.
> Is there a limit in the numbers of antennas that can be processed in
> imagr and uncon? If so, could you please point me to the relevant
> sections in the source code that needs editing or is there an easier
> way to increase the number of antennas?
The worst problem is that the format limits the number of antennas to
255 (BL = 256 * A1 + A2). It is true that IMAGR will ignore the
baseline so long as no calibration or flagging is done. I am surprised
that UVCON does not encounter this limit - that would be an error on its
There is a clever trick from Miriad which aips does not implement that
allows antenna numbers to be higher. But since these numbers are kept
in single-precision floats, there is a rather tight limit since these
floats get less accurate than 1.0 when the numbers are more than 2**24
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