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:
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.