Set Equatorial WCS
The Set Equatorial WCS command attaches an equatorial World Coordinate System ("WCS") to an image. The WCS allows the image to be examined and measured directly in units of Right Ascension and Declination.
Open this command from the View > World Coordinates menu.
The WCS Calibration requires the information shown in this dialog: (Right ascension, Declination) at a reference (column, row), an Image Scale, and an Equinox. This command inserts these quantities into the image header to enable world coordinate system functionality. This command is usually used to make a low precision or approximate calibration so that measurements, plots, and cursor readout can use World Coordinate units of arcseconds.
This command applies a WCS calibration to the image or image set. This calibration replaces any existing WCS. However, this command creates an Undo copy so that you can use the Edit > Undo (Ctrl+Z) command to restore the previous coordinate system. If you want to save the equatorial WCS calibration, save the image in the normal way.
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tip |
If the |
World Coordinate System, Image Coordinate System, Image Windows, Set Arcsecond Scale, Delete WCS
button
is pressed in the active Image Window, the calibration is applied
to all members of the