Function: BEAM
Purpose: Draw elliptical shaded beam (PGPLOT)
Category: PLOTTING
File: beam.c
Author: M. Vogelaar
Use: INTEGER BEAM(
SET, Input character*(*)
SUBSET, Input integer
SPATIAL, Input integer
DELTA, Input double precision array
CENTREXY, Input double precision array
FWHMMAJ, Input double precision
FWHMMIN, Input double precision
PA, Input double precision
LINES, Input integer
SLOPE Input double precision
SHAPE ) Input integer
BEAM Returns:
0 successful
-1 No valid shape selected
-2 No sky coordinates found in set
-3 Cannot find the grids for this beam!
SET GDS set (as returned by GDSINP).
SUBSET A single subset (as returned by GDSINP).
SPATIAL = 1 if both subset axes are spatial
= 0 other combinations
DELTA Grid spacing in X and Y. In the calling
environment this parameter is set to
header values of cdelt or ddelt or
the parameter is calculated some other way.
CENTREXY X and Y position of centre of ellipse in
world coordinates/grids.
FWHMMAJOR FWHM major axis of ellipse in degrees!
FWHMMINOR FWHM minor axis of ellipse in degrees!
PA Position angle of ellipse wrt. north in the
direction of the east, in degrees.
LINES Approximation of number of shading lines
for ellipse.
SLOPE Slope of shading lines in degrees.
This slope is defined in the system
of the grids i.e. slope = 0 is draws
shading line parallel to the X axis.
SHAPE 1: Plot shaded ellipse
2: Plot rectangle (e.g.IRAS beam)
3: Plot cross
Description: Draw an beam with an elliptical or rectangular shape or a
cross with specifications (origin, axes and projection
angle). The beam axes are specified in degrees and all
calculated ellipse coordinates are transformed to grids
using the transformation formulas for sky system and
projection. The position angle of the major
axis is wrt. +m axis. This angle is corrected for the
rotation of the image (CROTA).
If user wants shading (parallel line pattern only) you can
give the slope of the lines (wrt +X axis) in 'SLOPE' and the
approximate number of shade lines in 'DELTA'.
Updates: Dec 9, 1991: MV, Document created
Sep 19, 1994: MV, Rectangular beam implemented
Jul 7, 1997: MV, Cross implemented
Sep 30, 1997: MV, Completely rewritten 'pgbeam'.