In addition to computing the coordinates, the commands SOURCE /DRAW and PLANET /DRAW will also indicate the position of the requested source in the current plot (as defined by FRAME). Arguments to the /DRAW option may be:
The default argument of /DRAW is SYMBOL. Another very
useful option of the SOURCE command is SOURCE /FLUX
min_flux, that selects only the sources whose flux is larger that
the min_flux value.
Examples -- Below are a few examples of plots produced by the commands described in this section. A large variety of plots can be produced, depending on the user's purposes.
The following commands plot the position of the sources in the sky at 03:00 UT on April 1 2008, together with the position of planets (Fig. , only Jupiter is up):
CATALOG GAG_DEMO:SAMPLE.SOU ! define the catalog OBSERVATORY BURE ! define the observatory FRAME HORIZON ! plots the whole visible sky TIME 03:00 01-APR-2008 ! define the time & plot sun avoidance SOURCE /DRAW ! draw all sources from catalog PEN 1 ! select pen 1 (red) PLANET /DRAW ! draw all planets PEN 0 ! select pen 0 (black) HEADER ! label the plot.
The same plot, but seen in a different projection (from zenith position, see Fig. ), is produced by:
CATALOG GAG_DEMO:SAMPLE.SOU ! define the catalog OBSERVATORY BURE ! define the observatory TIME 03:00 01-APR-2008 ! define the time FRAME HORIZON ZENITH ! plots the whole visible sky SOURCE /DRAW ! draw all sources from catalog PLANET /DRAW ! and planets (only Jupiter is up) HEADER ! label the plot.
The following commands sequence plots the phase calibrators close to NGC 7027 (Fig. ):
CATALOG GAG_DEMO:SAMPLE.SOU ! selects the source catalog CATALOG GAG_DEMO:PHASE /ALTERNATE ! selecs the calibrators catalog OBSERVATORY BURE ! define he observatory TIME 03:00 01-JAN-1990 ! define the time SOURCE NGC7027 ! get source position FRAME EQ RA|PI*12 DEC|PI*180 45 ! frame EQ, centered on source, ! 45 degrees in total size PEN 1 ! red pen SOURCE NGC7027 /DRAW ! plot source position PEN 0 ! black pen SOURCE /DRAW /ALTERNATE ! draw phase calibrators HEADER ! label the plot