[daip] Re: One more CLCOR question

[Mark Reid]

Leonia,

On Thu, 17 Nov 2005, Leonia Kogan wrote:

> >That would seem to imply that the RATE column in the CL table
> >does nothing.  So why is it there?
>
> Why do you think that the RATE column in the CL table does nothing?

   Because you answered my question with a "YES":  (Note the
word "constant...correction" in the question.)

Reid's question:
> >>>Let me re-pharse my question.  If there is only one entry for
> >>>an antenna, will that result in a constant atmospheric (or clock)
> >>>correction, even if there input file has non-zero rate values?
> >>>
Kogan's reply:
> >>The answer is YES.


> As I understand the column RATE of a CL table having been applied to the
> data corrects
> the phase of the data adding RATE*DT. It is sort of approximation of the
> phase from time of CL table to the time of the data.
>
> Now about the input file for opcode 'ATMO'. I have always considered
> that the column DELAY (infile) is to correct DELAY column at the CL
> table  and the column DERIVATIVE (infile) is to correct RATE column at
> the CL table. This concept is used at CLCOR 'ATMO'

   I did the following test that seems to support the idea that
the rate values in the CLCOR ATMO infile have little, if any,
effect:

   I fitted for 2 parameters each for the atmospheres and clocks
and produced an input file for CLCOR with one entry per antenna.
If the rate parameters are used to extrapolate from the one time
given, then after fixing the data and re-fitting, the re-fit
results should be near zero.  This was true for the vertical
delays and clocks, BUT not for the re-fit rates which were close to
the original values.   It would be good if you try this test
(using DELZN and CLCOR) and see if you get the same results.
The data set on my anonymous FTP site (see earlier email)
is an excellent one for such tests.

Mark

=======================================================================

>
> Leonia
>
>
> Mark Reid wrote:
>
> >On Thu, 17 Nov 2005, Leonia Kogan wrote:
> >
> >
> >
> >>>Let me re-pharse my question.  If there is only one entry for
> >>>an antenna, will that result in a constant atmospheric (or clock)
> >>>correction, even if there input file has non-zero rate values?
> >>>
> >>>
> >>The answer is YES. Non-zero rate value is used to correct the RATE column at the
> >>CL table.
> >>
> >>
> >>
> >
> >   That would seem to imply that the RATE column in the CL table
> >does nothing.  So why is it there?
> >
> >mark
> >
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> >
> >
> >
>