Show Coordinates for all Systems

Show Coordinates for all Systems Toolbox

This window will display interactive coordinates for all the systems that are known for the displayed image. It is of most interest to when displaying NDFs as you can inspect pixel coordinates, as well as grid and sky coordinates.

Usually FITS images will have only two built-in coordinate systems, the grid one shown in the X and Y readouts and a celestial one, shown in the alpha and delta readouts, so this toolbox is of little interest to most FITS users at present. However, future standards will provide additional systems that describe things like the coordinates of each chip in a mosaic camera and the coordinates of the camera as a whole, as well as some celestial system.

NDF images have several coordinate systems associated with them:

GRID: the base coordinates shown in the X and Y windows. These are a continuous system that start at 1,1 for the pixel at the lower left.
PIXEL: the same as GRID, except that the middle of the lower left hand pixel is 0.5,0.5. These also have any NDF pixel origins added.
AXIS: these coordinates are those defined by any axis structures in the NDF. If none are present then these are the same as PIXEL.
SKY: if present this defines a celestial coordinate system.

Other multi-dimensional coordinate systems may be present, if so then their coordinates will also be shown. The software that produced these should describe what their meaning is (note that in general a description of each value, usually a label and any units, will be shown in the short help, just place the pointer over the value to see this). Note that if your NDF is using the coordinate system stored in its FITS extension then this may not apply and the systems available will be just the same as a FITS image.