### A Notes for IRAF users

CCDPACK is available for use from the IRAF command line. If it is available on your system then you should initialise it in the usual way:

cl> ccdpack

and all the commands that are available will be listed. You can also get help on the commands in the usual way. A useful document to consult is SUN/217.

The way that CCDPACK commands work from the CL is pretty much as is described in the preceeding sections, except you’ll need to write your scripts in CL and you’ll also be constrained to the choice of having to use CCDSETUP to define the CCD characteristics and package preferences, or not having its facilities at all (all the information about the behaviour and order of parameters through-out this document is also largely irrelevant). If you choose to use CCDSETUP (the default position) then you must run it to define the values of all the “global” parameters used by the other CCDPACK commands. You can spot global parameters in other commands as they all have a [G] indicator after their descriptions. You will not be able to set the values of these parameters by using eparam, but you can set their values on the command-line.

If this approach is too strange for you to accept then you can switch off this behaviour by issuing the command:

cc> use_globals

immediately after initialising CCDPACK. You can achieve this effect permanently by adding the command:

set CCDPACK_GLOBALS=no

to your login.cl. If you have already run another CCDPACK command before using use_globals then run the flpr command to make the change propagate. Once you have switched off the use of global variables then the CCDSETUP command becomes redundant and provides no useful functions (as do CCDSHOW and CCDCLEAR). Now when you run the other commands you can eparam all parameters.

One thing that you may find a problem for large sets of data is the loss of efficiency due to the conversion processes that CCDPACK uses to access non-NDF data. To get around this you can tell CCDPACK to output its results as NDFs by using the command:

cc> use_ndf

and then not adding a file extension to any output names. You can now process these new data sets much more efficiently. To get your images back into IRAF format do use a file extension type of .imh for the last stage of the processing pipeline.