All
successful use of astRead on a FitsChan is destructive, so that FITS header cards are
consumed in the process of reading an Object, and are removed from the FitsChan (this
deletion can be prevented for specific cards by calling the FitsChan
astRetainFits
function). An unsuccessful call of astRead (for instance, caused by the FitsChan not
containing the necessary FITS headers cards needed to create an Object) results in the
contents of the FitsChan being left unchanged.
The AST Object returned by
a successful use of astRead on an StcsChan, will be either a
Region or a
KeyMap,
depending on the values of the
StcsArea,
StcsCoords and
StcsProps attributes. See
the documentation for these attributes for further information.