[daip] CLCOR and the ATLBA

[Chris Phillips]

Sean, Eric

Please *do not* make any changes (yet!) to the main AIPS codebase as 
this needs more investigation on more than just CLCOR. One of the issues 
is this is the new DiFX software correlator not the LBA S2 correlator 
(ATLBA). It is just called ATLBA for compatibility.

Our understanding was that DiFX used the same handiness for the 
coordinate system as the LBA-S2 correlator so the ATLBA handling should 
be the same. Previous audits I have done of AIPS for ATCA and ATLBA 
indicated that, in general, the handiness was handled correctly (not 
guarantees all tasks do the right thing).

So either there is some odd bug in CLCOR, we don't understand the 
handiness of the DiFX coordinate system or there is some other subtle 
bug in CLCOR which does not account for the differences between ATLBA 
and DiFX.

Eric: I have mentioned DiFX to you ages ago ad promised to send you 
details of what is needed for support in AIPS. Adam Deller and I will 
eventually do this - but the age old lack of time means it has not 
happened. Given the VLBA and Bonn are going to use DiFX as well we need 
to address this sooner rather than later.

A specific CLCOR question: Does it change its behavior for FX and XF 
correlators? That is the biggest difference between ATLBA and DiFX.

Warwick Wilson is not around at the moment. Next time I see him I will 
ask about the handiness of ATCA and ATLBA.

Cheers
Chris