ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

106 CHAPTER 13. DATA CALIBRATION
automatically whenever a flat-field correction is required. Chapter 20 gives a more detailed
description the various calibration methods and their impact on the PDS.
It is possible to correct data for dark current and glitches only, save the result in an IDL
file, and then try different methods for transient and flat-field corrections (reloading the dark
and glitch corrected data before each new try). So the user must take care of what corrections
have been performed on a data set – including the order in which they have been performed –
before trying any other correction. It is possible to perform the same correction more then once
on a data set, though novice users are strongly discouraged from doing so. It is recommended
that you carefully read Chapter 20 if you really want to try this. The DATA STATUS window
displays some useful information about the number of times that each calibration was performed
on the data set. If the data set is loaded from an IDL restore command, then all indices start
at 900 instead of zero in order to indicate that the data status is unknown.
A data history has been designed in order to help the user to keep a track of all processes
which have been applied to the data set. This history can be displayed on the screen at any time
(using Data / Display History). The file data history.txt is then created in the current directory.
A log file of the whole x cia session can also be displayed on the screen (using CIA / Log
File). This log file contains all commands, warning and error messages of the current x cia
session. The default name of the log file is cia log.txt. This file is automatically overwritten at
the beginning of a x cia session unless the /noinit keyword is used. The user can also choose
another name by typing:
CIA> x_cia, logfile=’my_name.txt’
13.3.3.4 Example 2: testing several methods for flat-field correction
Let’s assume that the user wants to correct data from dark current, glitches and transient effects,
and then try several methods for the flat-field correction. Assuming that a user input frame (an
IDL 32×32 array called my flat in the following) is used as flat-field, it is necessary to load it
using the INFLAT keyword.
Hence, the sequence of commands would be the following:
1. Start a CIA session.
2. Start x cia with the following:
CIA> x_cia, inflat=my_flat
3. Choose AOT Type (default is raster scan).
4. Data / Load / SSCD
5. Data / AOT Info
6. Process / None
7. Dark / User Input
8. Deglitch / Spatial
9. Transient / SAP Model Fitting
10. Process / Selected