User Coordinates

The users coordinate system is mapped onto the current zone using a set of MAP commands. Mapping commands prefixed by the letter "A" will map the limits supplied onto a area inside the current zone leaving room around the perimeter for axis annotation, labelling etc. Mapping commands prefixed by the letter "Z" will map the user limits onto the edges of the current zone. The following mapping commands are available:

qcl>AMAP    GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>AMAPXL  GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>AMAPYL  GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>AMAPXYL GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>AMAPS   GRP_AXISRA,GRP_AXISDEC,GRP_ROLLANGLE,
             GRP_XCEN,GRP_YCEN,GRP_WIDTH,GRP_HEIGHT
qcl>AMAPI   GRP_XCEN,GRP_YCEN,GRP_WIDTH,GRP_HEIGHT
qcl>ZMAP    GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>ZMAPXL  GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>ZMAPYL  GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>ZMAPXYL GRP_XLEFT,GRP_XRIGHT,GRP_YBOT,GRP_YTOP
qcl>ZMAPS   GRP_AXISRA,GRP_AXISDEC,GRP_ROLLANGLE,
             GRP_XCEN,GRP_YCEN,GRP_WIDTH,GRP_HEIGHT
qcl>ZMAPI   GRP_XCEN,GRP_YCEN,GRP_WIDTH,GRP_HEIGHT

The parameters GRP_XLEFT, GRP_XRIGHT, GRP_YBOT, GRP_YTOP define the window in user coordinates. Note that GRP_XLEFT can be greater than GRP_XRIGHT and GRP_YBOT can be greater than GRP_YTOP.

The following letters "XL", "YL" and "XYL" will set up logarithmic mapping on the appropriate axes. Remember that the user limits must then be greater than zero for the logarithmic directions.

AMAPS and ZMAPS provide centred mapping for images of the sky. All the sky mapping parameters must be in degrees.

 
qcl>AMAPS 0.0,90.0,10.0,0.5,0.5,1.0,2.0

This command will set up a sky mapping with a local origin at the North Celestial pole and a local roll angle of 10 degrees to North. The centre of the plot will be at the local spherical position 0.5,0.5 and the mapped area will be 1.0 degree wide and 2.0 degrees high. These commands automatically set up the appropriate spherical coordinate transformations.

AMAPI and ZMAPI will set up a mapping for an image but without the associated spherical coordinate transformations set up by AMAPS and ZMAPS.