The Imager PIPELINE tools
With ALMA or NOEMA, you may end up with an observational data set
that contains several sources, each of them observed with
a number of spectral windows of different spectral resolutions,
covering many spectral lines.
The bookkeeping of such data sets can be intricate. To help the
users to focus on the science, we have developped a pipeline
(namely a suite of scripts named
all-*.ima) that automates the whole imaging process in this case.
This pipeline can be run through the
PIPELINE command,
or through a control panel launched by the
PIPELINE /WIDGET command.
The pipeline control parameters are available in the
ALL% global structure,
and can be checked using the
PIPELINE ? command.
The pipeline is intended to handle all spectral sub-bands for a single receiver tuning of the interferometer, with
the data (possibly with several observing dates) for each sub-band and each source stored in a separate file
(in UVFITS or GILDAS UV format).
The principle is to gather all UV tables in a sub-directory (named
./RAW/ by default), and to store the results of the
various processing steps (Self Calibration, Spectral line
extraction, Imaging) in different sub-directories (respectively
named
./SELF/, ./TABLES/, ./MAPS/ by default).
The behaviour of the Imaging step depends on the pipeline mode,
ALL%MODE, that
can be controlled by the
PIPELINE /MODE option. It also depends on
whether a
CATALOG is used or not, and on the
ALL%RANGE[1:3] variable that
controls the velocity span and resolution.
- CONTINUUM Mode:
In this mode no data cube is produced. Only continuum images are created, with no attempt
to remove any contaminating line emission.
- SURVEY Mode
In this mode, there is also no spectral line emission filtering. Full data cubes are
produced, at the spectral resolution specified by
ALL%RANGE[3]. No continuum
image is produced: continuum can be later extracted through the
MAP_CONTINUUM
command.
- SPLIT Mode
- Without a spectral line catalog, the Imaging step will make
no attempt to identify spectral lines, and thus no attempt to image
each line separately. Instead, each “high spectral resolution” UV table will be imaged
completely. An automatic estimate of the continuum level is made,
and is imaged separately from the continuum-subtracted data. At
the end of the process, the deconvolved “continuum” image
is added back to the spectral image.“`Low spectral resolution” data only produce
a continuum image.
This mode is appropriate for e.g. low spectral resolution data,
very wide lines, and/or nearly confusion limited data with many spectral lines.
- With a line catalog, a user-specified velocity range is imaged
separately around each line in the catalog that falls into the
observed frequency coverage. Continuum and Line are separated, but
no attempt is made to add back the continuum data at end.
- ALL Mode
This mode is similar to the SPLIT mode, except that no attempt is made to produce
continuum-free line data cubes. The line data cubes also include the continuum data.
This mode is appropriate when the continuum emission has spatial variations of
its spectral index.
Naming conventions apply to identify which data set covers which spectral line.
Subsections