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What global variables are available in - Knowledgebase / Offline Data Reduction and/or CASA - ALMA Science

What global variables are available in

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The global variables SPACESAVING, USEMS, DOSPLIT, and DOCONTSUB can be set prior to executing The variables can be used independently or in conjunction.

USEMS can be set to use pre-imported measurements sets(MS) rather than import them from the ASDMs in the raw directory. You must have created the directory calibrated and put the imported raw MSs uid*.ms into individual working directories named uid*.calibration inside the calibrated directory. It can be set to either 0 or 1 with the following meaning.

USEMS = 0 same as not set, ASDMs will be imported from the raw directory

               = 1 MSs have been pre-imported in the calibrated directory

SPACESAVING limits the disk space usage during and after execution of the script. It can be set to an integer from -1 to 3 with the following meaning.

SPACESAVING = -1 do not check disk space

                            = 0 same as not set (all intermediate MSs are kept)

                            = 1 do not keep intermediate MSs named *.ms.split 

                            = 2 do not keep intermediate MSs named *.ms and *.ms.split 

                          >= 3 do not keep intermediate MSs named *.ms, *.ms.split, and * (if possible)

With SPACESAVING=0, the required additional diskspace is up to 14 times as large as the delivered data (products and rawdata) while with SPACESAVING=3 (maximum savings), it is up to 6 times as large. The script will estimate the required disk space and will not execute if there is not sufficient free space available.

DOSPLIT can be set to create the * MSs, containing the only the calibrated data and science spectral windows (spws). 

DOSPLIT=True will force the creation of the * MS.

DOSPLIT=False is the same as not setting DOSPLIT at all. In that case, the script will only create the * MSs in the case there was manual imaging (i.e. not pure pipeline imaging) performed during QA2.

DOCONTSUB can be set to re-create the continuum-subtracted MSs for line imaging. This is only relevant for pipeline-imaged data.

DOCONTSUB=True creates the continuum-subtracted MSs. In this case runs the first imaging stages. From Cycle 10 onwards, DOCONTSUB will automatically be run if the pipeline used self-calibration.

DOCONTSUB=False is the same as the default of unset. Continuum subtraction will not be applied.

For example, after initiating CASA in the script directory, the following commands would use pre-imported MSs and the highest degree of spacesaving and ensure that the calibrated data is split out into new * MSs at the end.


USEMS = 1<



For more information, see the ALMA QA2 Data Products document.