Features of the Primitives

Primitives are the Perl scripts which actually call the applications to do most of the data processing. All of the imaging recipes are, in principle, independent of the instrument. However, some recipes are inappropriate; for example, the NOD_CHOP family of recipes are intended for mid-IR imaging with Michelle, but not the JITTER_SELF_FLAT family. The generality comes in part from translations of relevant header information into a generic form used by ORAC-DR.

Not all the following steps apply to all recipes. Consult the reference section to see summaries for each recipe. The steps are presented in normal order of appearance.

The main primitives pertinent to each step are listed in bracketed italics, should you wish to tailor the recipes. These are found in $ORAC_DIR/imaging tree, unless they start with general/ when they are located in $ORAC_DIR/general. Note the some may be instrument-specific variants, either given explicitly or with the <instrument> token, which means substitute the instrument name in uppercase.

While those listed form the bulk of the primitives, there are many not listed here, mostly those for recipe initialisation called <recipe>_HELLO_. and for recipe steering, which control when to perform certain operations, called <recipe>_STEER_. The first of these is normally left unchanged unless there is a need to add more steering parameters passed to the steering primitive. The steering primitive itself is only modified for such new steering parameters, and if the observing pattern or sequence is different from what the recipe is programmed to expect. Other primitives not mentioned here are tied closely with single recipes, usually to create and file calibrations.