[daip] UVLIN & UVLSF questions

[Bryan Butler]

i'm a bit confused about the values of "FLUX" to use for 
UVLIN & UVLSF.  i always have been, but in the past i just
tended to trial and error until i found the right level
to use.  but i decided to really try to figure it out.  the 
explain file for UVLIN says:

  FLUX.......Max. residual flux allowed for unity weight. This
             should be 6-8 times the rms noise for a single
             channel in a 10 second integration.

does it *really* mean in a 10 second integration, or is it
in the integration time that is in the data (i.e., the rms
per channel visibility)?  if it *is* 10 seconds, why?  i
can find nothing in the data that scales the residual or
the flux cutoff from the true integration time to 10 seconds, 
so i suspect that it's the true integration time, but if so,
why does it so explicitly say "in a 10 second integration"
in the help file?

now, the UVSLF explain file says:

  FLUX.......If the residual flux in any channel used to fit the
             baseline exceeds FLUX, then the spectrum for that time, IF,
             and polarization is fully flagged.  <= 0 => 1.0E20

which is more straightforward in a sense, but gives no guideline
(similar to the 6-8 times rms in UVLIN) to the user.  but then
further down in the explain file for UVLSF it says:

      UVLSF differs from UVLIN in a number of ways. UVLIN does its
  flagging only on the peak residual in the channels selected for
  fitting and scales the peak by the square root of the
  integration time before deciding on flagging.  This is correct
  for peak residuals due solely to thermal noise but is an added
  confusion to the user.  In any case, you should set the FLUX
  cutoff at a conservative level (6 - 8 times the expected sigma
  in the usual integration time).  

OK - here is the same recommended factor of 6-8 (why isn't it
somewhere above, where folks will actually see it?).  but, is the 
"usual" integration time the one that is present in the data, or 
10 seconds (one could argue that 10 seconds is indeed the "usual" 
integration time at the VLA anyway)...


and one final question - are both UVLIN and UVLSF currently
supported?


	-bryan