CLASS is a
GILDAS1 software for reduction and analysis of (sub)-millimeter spectroscopic
data. It is daily used to reduce spectra acquired with the IRAM 30m
telescope.
CLASS is currently used in many other facilities (
e.g.
CSO, HHT, Effelsberg) and it is considered for use by Herschel/HIFI.
CLASS history started in 1983. As a consequence, it was written in
FORTRAN 77 and tailored to reduce pointed observations. On-The-Fly
support was added in the 90s but it showed limitation as the quantity of
OTF data increased quickly. One year ago, we decided to fully rewrite
CLASS in FORTRAN 90 with the 3 following goals: 1) clarifying
satisfying features with backward compatibility in mind, 2) improving
code readability to simplify maintenance and 3) easing reduction of large
OTF data sets. This memo is describing the
current state of affair
with a particular emphasis on changes in the program behavior. Future
foreseen changes (linked to the increase of receiver instantaneous
bandwidth like an improved conversion from frequency to velocity axis)
will be described in a future memo.