class Continuum and Line Analysis Single-dish Software - IRAM

3.1. GENERALITIES 15
• SET SOURCE Name for the source name; same specifications as SET LINE.
• SET SCAN s1 s2 for a range of original scan numbers. Scan numbers should not be confused
with Observation numbers (the numbers by which an observation is uniquely identified).
They are essentially “history” numbers defined by the acquisition system, but usually with
different “observations” (in the class meaning) for a single scan. The scan number is kept
only for bookkeeping purpose.
• SET TELESCOPE Name for the Telescope name. For the IRAM 30-m telescope, the telescope
name contains coded into the last 3 letters the backend used for the observations. Similar
conventions are used for spectra coming from Plateau de Bure Interferometer.
• SET TYPE Name specifies on which type of observations you deal with: “Continuum”, “Line”
or “Skydip”.
The tolerance parameter defined by SET MATCH also influences on the position searches, since this
parameter (in the current angle unit) is used to check agreement with the specified limits. Another
option to the FIND command is /ALL which enables to find all the versions of all observations
satisfying the selection criteria (otherwise only the most recent version is selected). Note that
the system is intended to work only with the last version of observations, so that the use of the
/ALL option should remain exceptional.
Finally, the SET SORT force the FIND command to sort all the entries of an index in ascending
order of a key parameter (e.g. lambda or beta offsets). SET SORT number implies the default
order.
3.1.5 R and T Memories
class keeps 2 observations in memory, in two different buffers, called R and T. The R memory is
the only one that may be accessed directly; the T memory is only used for operations on spectra
(additions,...). The GET n command places the spectrum corresponding to entry number n in the
R buffer, while the previous R content is stored in the T buffer. The command SWAP exchanges
both memories.
3.1.6 Large Set of Spectra
It is today possible with the IRAM–30 m to map a square degree field in CO (2-1). As an order
of magnitude, this gives a final spectra cube of about 10 6 spectra with a slightly oversampling of
4 ′′ . An observer who has just spent a few hours observing the same source in OTF mode may
want to process all the dumped spectra at once even though they do not belong to the same scan.
The LOAD command gathers all the individual spectra currently in the index as a 2D array for
future work, in particular visualization. This requires that all the spectra currently in the index
are coherent, i.e. same source name, same line name and above all exactly the same frequency
sampling. The latter can easily be achieved just by resampling. No checking is currently done
about this, i.e. this is currently the responsibility of the observer to ensure a coherent frequency
axis. The /INDEX option of commands like PLOT or BASE modifies there behavior to directly work
on the 2D array defined with the LOAD command.
Nota Bene: The STRIP command which is producing a Velocity-Position plots, is obsolescent.
Indeed the same functionality can be achived by the combination LOAD; PLOT /INDEX if the
index is correctly choosen. And the LOAD command is much more powerful.