class Continuum and Line Analysis Single-dish Software - IRAM

Chapter 1
Introduction
class is a software package for reducing spectroscopic data obtained on a single-dish telescope.
It also has basic functionalities to reduce continuum drifts like pointing or focus.
The originality of class with respect to similar systems already in use is in the way an
observation may be identified. In addition to the traditional scan number which can be used to
uniquely refer to an observation, the system also enables one to use Selection Criteria as in a
data base management system. This faculty, added to a powerful command monitor, sic, allows
easy manipulation of large volumes of data; the list of observation numbers to be added to get
the mean spectrum at one position need no longer be typed in, but may be found by class itself.
On a standard installation, class is entered by just typing class. class is divided in different
parts, called “Languages”, which have somewhat independent functions:
• Language LAS contains all the general utility functions to handle the data structure, plot
the spectra or drifts and calibrate them.
• Language ANALYSE contains functions to analyse calibrated spectra in more detail.
• Language FIT gathers the spectra fitting functionalities.
Those languages are described in this manual. In addition, class imports many functionalities
defined and documented in other gildas packages:
• The command line interpretor is imported through the SIC (basic), GUI (for widgets) and
VECTOR (miscellaneous) languages.
• The plotting possibilities through the GTVL (basic graphic actions), GREG1 (curve plotting),
GREG2 (image plotting) and GREG3 (data cube plotting) languages.
• And the ephemerids and atmospheric contributions through the ASTRO language.
In addition to this manual, the reader should thus consult the sic manual, and for further
processing, the greg manual.
This version of the class documentation reflects the full rewritting of class in FORTRAN90.
In this process, many things have been changed, hopefully improved. If you are an experienced
class user, you may first want to consult the IRAM memo which describes only the changes in
this version of class.
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