[daip] keyword for aberration correction

[Eric Greisen]

Walter Brisken wrote:
> Today at the VLBA Test and Development meeting I mentioned that with the 
> software correlator I plan to use UVW coordinates that are corrected for 
> the various relativistic effects (aberration, etc).  I believe this should 
> be made clear in a table keyword.  I would like the keyword (call it 
> ABERCORR here, subject to other suggestions) to have at least three 
> levels:
> 
> ABERCORR = UNCORRECTED -- the uvw values are those returned by calc
> ABERCORR = APPROXIMATE -- a correction, acturate to some level, is made
> ABERCORR = EXACT -- all corrections consistent with the delay model are made
> 
> Does this sound reasonable?  I would suggest making this an optional 
> keyword in the UV_DATA table of FITS-IDI files.  The default if left 
> unspecified would be UNCORRECTED.

Did you have any intended use for this keyword other than informative?
UVFIX does its thing and does not care how good the old u,v,w are and 
the rest of AIPS takes them at face value in any case (having no other 
choice).

Eric