World Coordinate System
The term "World Coordinate System", or "WCS" refers to a coordinate system that describes the positions of objects in the sky rather than in the columns and rows of an image. Mira adopts the WCS definition of the FITS format standard. This standard proscribes both the way in which world coordinates are expressed in the image header and also the image coordinate systems available for FITS format images. Any FITS image meeting the FITS WCS standard will be properly interpreted by Mira. The WCS is implemented using a specific set of header keywords.
For images containing WCS information, Mira shows image coordinates, measurements, and plots in either WCS units or the native array system of (column,row). For WCS calibrated images, you can select which plot coordinate system to use.
Mira implements FITS WCS support using the dynamic link library FitsWcs.dll. This library resides in the Modules\ subdirectory. If this DLL is not present at startup, Mira will operate normally but will not display world coordinates for FITS images even though they have WCS information.
Image Coordinate System, Plot Coordinate Systems, Image Coordinate Readout, Point Measurements, Image Window, Astrometric Calibration, Set Equatorial Scale, Set Arcsecond Scale, World Coordinate System Keywords, Coordinate Systems