[daip] apcal

[Ketan Desai]

I put in this message before I left.

> Over the last several weeks, APCAL has acquired a warning
> message as follows:
> 
> APCAL1: *** At least one source had identically zero flux
> APCAL1: ***  Usually this means you forgot to run SETJY.
> APCAL1: ***  This may be important if you have a very
> APCAL1: ***  bright source (masers?).
> 
> However, when you're reducing VLBI data, it generally is the
> case that no source has a flux density in the SU table,

right, before I got in there, APCAL would refuse to run until
you had run SETJY to set the flux to 1.0 in the SU table.

> because there is no equivalent to 3C 286.  VLA users have
> a source flux, but they don't run APCAL.  So I don't know
> why this message was put in.  Maybe it applies to some

see above.

> spectral-line observations, but for most continuum observations
> of strong sources or phase referencing, it just confuses the
> user.  It seems to me that it should be taken out, or else it

It also informs the user that something -wrong- is being done.
They are asking for opacity calculations to be performed without
estimating in anyway way the strength of their source.

> should be clearer.  Most VLBI users never run SETJY, so
> they will get very confused when told they forgot it.

Its not up to me anymore but I would suggest modifying the
warning rather than removing it.  It has a purpose and is ignored
the user's peril - especially at high frequencies.



-- ketan
M.O.T.U.