can also be used to write a visibility FITS file. In addition
to the keywords used when reading visibility datasets, fits
options to control
extra processing performed on the visibilities.
is more sophisticated at reading FITS files
than writing - note the following caveats carefully.
can cope with only a single pointing of a single
source, with a single frequency setup and single antenna array
configuration (note that, unlike earlier versions, fits
does quite limited checks to see
if these conditions are met, and quite happily will
use the relevant parameters of the first record.
assumes that the data are a single IF
band, with a constant frequency increment between channels. If presented
with multiple spectral windows (multiple IFs), an average frequency and
increment will be used. This is very undesirable. If you do
will issue warnings about frequencies deviating from
linearity. These warnings should be taken seriously. To avoid this, use
the select or line parameters to force fits
out a single spectral window.
does not save Miriad calibration tables. However
does give you the option of applying the calibration, as
it writes out the data (see the
- Miriad allows you flexibility in the choice of polarization
correlations that you can write out. On-the-fly polarization
conversion can be performed. However AIPS will refuse to read in a
number of the possibilities that Miriad allows. In particular, AIPS UVLOD refuses to load visibility data where there are
three different sorts of polarization correlations (rather than the
more usual 1, 2 or 4 sorts).
Typical inputs follow:
||Name of input Miriad dataset.
||Write out a visibility FITS file.
||Output FITS file - probably upper case for AIPS.
||Select appropriate data.
||Select appropriate polarizations.
||Leave unset to apply calibration,
||or turn off all calibration.