class Continuum and Line Analysis Single-dish Software - IRAM

Chapter 4
Developer Manual (04-dec-2006)
Please check directly the class sources to get the most up-to-date information.
4.1 Internal class Format
4.1.1 Contents of one observation
Data, i.e. observational parameters as well as spectra, is organized in the following way:
• One observation is self-contained. All the information needed to reduce it is recorded on
the same few disk blocks. It may be one spectrum or one continuum drift.
• Each observation is divided in several sections, containing header parameters or data:
– General information (date, times, local coordinates, sequence number, ...)
– Positional information (source, name, astronomical coordinates, epoch, offsets, ...)
– Spectral information (number of spectra, line names ans frequencies, resolutions, number
of channels, ...)
– Data
– ...
Each type of section is known by the system by means of an integer code. It is not required
that all sections be present. Some are written by the observing program at the time of
the observations. Some may be dropped during the reduction, being replaced by new ones
describing the results of the different stages of the reduction procedure.
• Each observation begins with the following words:
length content
(bytes)
4 ’2’ (identification code)
4 number of logical blocks
4 number of byte describing the observation
4 address of the data section (bytes)
4 length of the data section (bytes)
4 the number of header sections
31