Description
This function can be used to average calibration solutions over fields,
spectral windows, and/or time. It is useful for smoothing solutions in
time, and for re-identifying solutions for field and spectral window, as
may be required in spectral line observations where doppler tracking is
used on the target source, but not on the calibrater (and hence the
spectral windows for each source are different). This function
currently supports averaging of calibration tables containing Jones
matrices with diagonal elements only (G, B, T). For B, the averaging is
done for each channel separately (there is no channel averaging).
Handling of tables with off-diagonal elements (D, F) will be supported
in the future.
The fldsin parameter takes a vector of integers; the fldsout parameter must be a single integer (used for all fldsin) or a vector of integers, one for each in fldsin. They
must both be specified.
The spwsin parameter takes a vector of integers; currently,
only one spwout can be specifed (all spwsin will be
averaged to this). They must both be specified. Use append=T
to write more than one output spectral window to the same file. All
input and output ids must exist in the measurement set.
Use the t paramater to set the interval over which solutions
from the input field ids and spectral window ids will be averaged. Note
that simple solution time-averaging can be achieved by making fldsin=fldsout and spwsin=spwout. If this parameter is
negative (the default) the solutions are just copied.
Use the mode parameter to choose between 'RI'= averaging real
and imaginary (coherently) or 'AP'= averaging amplitude and phase
(incoherently). Use 'AP' to avoid reduction in amplitude if the
solution phases drift appreciably during the averaging interval, t.
Example
c:=calibrater('3C273XC1.MS');
c.calave(tablein='3C273.gcal', tableout='3C273.gcal2',
fldsin=[1,2],spwsin=[2,3],fldsout=7,spwout=13,
t=300, append=F, mode='AP')
c.done();
This example will average solutions from field ids 1 & 2 in
spectral windows 2 & 3 in 300 second intervals and identifies the result
as field id 7 and spectral window 13. The averaging is incoherent.
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Up: calibrater - Tool
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2006-10-15