Mixing Native Objects with Other FITS Cards

Of course, any real FITS header will contain other information besides AST Objects, if only the mandatory FITS cards that must accompany all FITS data. When FITS headers are read in from a real dataset, therefore, any native AST ObjectObject descriptions will be inter-mixed with many other cards.

Because this is the normal state of affairs, the boolean (integer) SkipSkip attribute for a FitsChanFitsChan defaults to one. This means that when you read an Object From a FitsChan, any irrelevant cards will simply be skipped over until the start of the next Object description, if any, is found. If you start reading part way through an Object description, no error will result. The remainder of the description will simply be skipped.

Setting Skip to zero will change this behaviour to resemble that of a basic ChannelChannel (ยง15.12), where extraneous data are not permitted by default, but this will probably rarely be useful.