7 Data reduction procedures

7.1 Direct imaging

The basic data processing of direct CCD images includes the following steps:

For detailed data reduction procedures for direct imaging we recommend that you read the ``User's guide to the CCDRED Package'', Francisco Valdez, 1987, (NOAO/IRAF group). N.B. It is assumed that Biases and darks are identical, which is a very good approximation with our present detectors.

8.2 Spectroscopy

7.2.1 Overview

The basic data processing for spectroscopic data includes the following steps, the first ones being similar to data processing of direct images:

7.2.2 The MULTIRED package

The package MULTIRED has been written under IRAF by O. Le Fèvre to process MOS/SIS multi-slit data following the above steps. You can get this package via ftp . The file multired.tar is a tar file containing all the necessary files. To unpack and recreate the files, type the command:

tar xvf multired.tar
Proceed with the installation of the package in IRAF, by following the steps described in the file README. MULTIRED is a very efficient package which helps you keep track of slit numbers, works on multiple images per mask, and performs the data processing steps in a painless sequence to produce flat/sky corrected 2D spectra, as well as wavelength and flux calibrated 1D spectra. On line help is available for each MULTIRED task.

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