ECHRDUCE - Reduce object frames

Purpose:

Script to reduce a set of object frames with ECHOMOP.

Language:

C shell script.

Description:

This script reduces a series of object frames using ECHOMOP.

The output files are named ob_File where File is the name of the input object frame.

Usage:

This script can simply be invoked from the shell; in this case the script will prompt for a list of object frames to be processed Alternatively, the input frame names can be supplied on the command line, for example:

   % echrduce run0800 run0801 run0802 run0856 run0857 run0858

If wildcarding facilities are available in your shell, you can use them to simplify the command line, for example, the above would become:

   % echrduce run080[012] run085[678]

in the C shell. This wildcarding facility is available when the script prompts for a list of input images.

In practice, invocation from your shell is unlikely to be a good method of using this script as 3 environment variables defining the CCD output characteristic and ECHOMOP reduction structure file name are required. Use of these variables is summarised below.

Arguments:

If supplied, command-line arguments must be in this order:

1. List of files. List of files to be processed.

Missing command-line arguments are prompted for.

Source code:

The script source code is available here.

Notes:

1. If needed, the input parameters can be input at the command line thus:

      % nohup echrduce filename [filename...] &
   

   the nohup command will ensure that the script continues to run even when you have logged off the system. The & at the end of the line will run the script in the background.

2. This script is designed to be used as part of an automated échelle data reduction package. If you intend to use it for this purpose, you should not change the name of the output frames, ob_`File'.

3. When this script is invoked, 3 environment variables defining the output characteristics of the CCD used, and the ECHOMOP reduction structure file used must be defined. These environment variables are used:

   $EchFile

   Name of the ECHOMOP reduction structure file.

   $Gain

   CCD output transfer function in photons per ADU.

   $RDN

   CCD readout noise in electrons.

4. A file flatfield containing a flat-field frame prepared by the script prepflat should exist in the working directory. You can alter the name of this file, see comments in the script.

5. The scripts prepobjs, prepbias and prepflat should be used to prepare data for processing with this script.

6. This script is designed to be called by a master reduction script. See the example scripts preprun1 and preprun2 for details.