[daip] CLCOR 'OPAC' & VLBA correlator question

[Michael Bietenholz]

   For a VLBI data set, the VLBA correlator has an atmosphere model
which it used for delays etc., but does it apply any sort of opacity
correction?  In particular, is running CLCOR, OPCO = 'OPAC' a good
thing to do for VLBA stuff, or would it apply the opacity correction
twice, and therefore be bad?  (I'm aware of the fact that this opacity
correction only very approximate, but its better than nothing).

                thanks,        michael b