A uv table is a specific 2-D Gildas table, with a few additional
informations in the header, and a special interpretation of the data
organisation.
In a standard uv table, each line describes a visibility.
Here a line designate either the first or second axis of the
table, and a column the other one. uv tables may appear in
both orders. The default one is line on 1st axis (.uvt
ordering, used by most application). The .tuv ordering
obtained by a 21 transposition is used essentially for display, as in
this case the column has the same meaning as for the
COLUMN of
GREG .
The number of lines of a uv table is thus the number of visibilities described
in the table. Each column of the table stores a particular property of the
visibilities, namely:
- Column 1
- U in meters;
- Column 2
- V in meters;
- Column 3
- W in meters or Scan number;
- Column 4
- Observation date (integer
CLASS/
CLIC Day
Number3);
- Column 5
- Time in seconds since 0:00 UT of above date;
- Column 6
- Number of the first antenna used to measure the visibility;
- Column 7
- Number of the second antenna used to measure the visibility;
- Column 8
- Real part for the first frequency channel;
- Column 9
- Imaginary part for the first frequency channel;
- Column 10
- Weight for the first frequency channel;
- Columns 11-13
- Same as column 8-10 but for the second frequency
channel, or for the second Stokes parameter of this channel.
- ...
- etc...for all channels
- Columns N-ntrail+1 ... N
- Trailing columns after the channel visibilities.
If a uv table describes nvis visibility spectra composed of
nchan frequency channels, each with nstokes Stokes parameters,
the size of the table will thus be:
nvis lines of 7+3*nchan*nstokes+ntrail columns, where ntrail
is the number of trailing columns.
