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Display Tools

The IMAGE command and the GreG part of the GRAPHIC program can be used to display images (contour maps) and UV data. To display images, use the following basic commands:

    IMAGE Filename    ! Connect to image file
    LIMIT/RG          ! Compute limits of plots
    LEVELS List       ! Set contour levels 
    RGMAP             ! Draw contours
    BOX/UNIT SEC      ! Draw box, using arcseconds as angular units
See the GreG and GILDAS manuals for further details.

UV data also needs to be displayed. The UV tables are produced naturally in visibility order, which is not suited for display. Task TRANSPOSE or command TRANSPOSE in language VECTOR must be used first. We recommend these file extensions: .UVT for UV tables, and .TUV for their transposed counterparts. A .TUV table has the following format

Column 1   U coordinate in meters
Column 2   V coordinate in meters
Column 3   W coordinate in meters
Column 4   Day (in CLASS units, a Modified Julian Date)
Column 5   Time in seconds since 0:00 UT
Column 6   Start antenna
Column 7   End antenna
Column 8   Real part of channel 1 visibility
Column 9   Imaginary part of channel 1 visibility
Column 10  Weight of channel 1
Column 11, 12, 13,  etc. for other channels
.TUV tables can be plotted using the following commands
    COLUMN X Ix Y Iy/TABLE Table.TUV ! Ix and Iy are the interesting
    LIMITS                           ! column numbers
    POINTS
    BOX
or directly using Tables as SIC variables
    DEFINE IMAGE UV Table.TUV READ
    LIMITS/VARIABLE UV[Ix] UV[Iy]    ! Ix and Iy as above
    POINTS UV[Ix] UV[Iy]
    BOX

The GRAPHIC program can display data cubes in bit-map format.



Gildas manager
2001-04-24