### 17 Introduction

This part of the cookbook provides a set of scripts to assist with various aspects of reducing CCD images. The scripts embody some of the ‘tricks of the trade’ of reducing CCD data and either automate part of the process by allowing you to process a set of files or string several individual applications together to provide some useful functionality. The scripts are written for the Unix C-shell and should be run from the Unix command line. They suffer from the usual limitation of scripts that they are neither as flexible nor as robust as an application program. However, they do provide additional useful functionality. Also, they have been deliberately kept simple and commented in order to make it easy for you to modify them for your own purposes. The use of Starlink applications from shell scripts is discussed further in SC/4: C-shell Cookbook[4].

The scripts available are:

• convert files to a new data format (Section 18),
• clip an image (Section 19),
• process compressed files (Section 20),
• examine specified FITS keywords (Section 21),
• automatically scale an image display (Section 22).

On Starlink systems the scripts are kept in directory:

/star/examples/sc5/scripts

You should copy the scripts to your current directory before using them. The examples included in the following descriptions of the scripts assume that your current directory is the subdirectory targets of the example data directory used in the recipes in the previous part of the document and that you have worked through the previous recipes for reducing CCD observations (Sections 9 to 14). The examples should work as given in this case.

The current collection of scripts is not comprehensive. If you have a script which you think could usefully be included in this document then please contribute it. Similarly, suggestions for additional scripts which we could provide are welcome. In both cases contact the Starlink Software Librarian (e-mail starlink@jiscmail.ac.uk) in the first instance. New versions of the cookbook including additional scripts will be issued from time to time.