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Basic Information on conterr
Purpose: Continuum subtraction error estimate, when using UVLIN.
Categories: uv analysis
Given an image of the continuum in a spectral line experiment,
CONTERR estimates the residual continuum artifacts that will
be present after continuum subtraction using UVLIN. The results
are intended to be indicative, rather than rigorously accurate.
The peak value and location of the errors are approximately
correct, but the actual error pattern will differ significantly
from that presented here.
This task essentially just evaluates the expressions given in
Table 1 of "An analysis of visibility-based continuum
subtraction" by Bob Sault. CONTSEN makes plots of noise
amplification factor of tasks such as UVLIN, AVMATHS, and
An estimate of the continuum. It should be either a dirty image
or a deconvolved/restored image. No default.
The order of the polynomial fit in UVLIN, either one or two
numbers can be given. If two, then CONTSEN determines the error
for order(1) to order(2) inclusive. The default is to determine
the noise sensitivity for first order only.
Total spectral bandwidth, in GHz. Default is 0.008 (i.e. 8 MHz).
The image resolution, given as the FWHM of the corresponding
gaussian, in arcsec. This is the same as the FWHM that RESTOR
would determine. The default is to get the information from
the input image. Two values can be given, being the FWHM in
x and y respectively (i.e. the position angle is assumed to
be along one of these axes). If only one value is given, the
gaussian is assumed to be circularly symmetric.
Note that high order fits are very sensitive to this parmeter.
An output image containing the error images. The default is
no output image.
Extra processing options. Several can be given, separated by
commas. Minimum match is used. Possible values are:
shift Determine an optimum shift of the phase centre to
be applied before the error is evaluated. This
shift will minimise the error in some sense.
Revision: 1.5, 2013/08/30 01:49:21 UTC
Generated by email@example.com on 21 Jun 2016