Resetting the Calibration Models (delmod and clearcal)

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4.6.3 Resetting the Calibration Models (delmod and clearcal)

Whenever calibration tasks are run, the models associated with the MS will be overwritten. Sometimes, however, one would like to completely remove the model and the task delmod can perform this functionality:

#  delmod :: Deletes model representations in the MS
vis                 =         ’’        #  Name of input visibility file (MS)
otf                 =       True        #  Delete the on-the-fly model data keywords
scr                 =      False        #  Delete the MODEL_DATA scr col (if it exists)
async               =      False        #  If true the taskname must be started using
                                        #   delmod(...)

To do so, the para,eter otf should be set to True. delmod can also be used if for any reason a MODEL_column was created and should be removed to avoid confusion between the on-the-fly model and the MODEL column (the MODEL_DATA column was required in CASA 3.3 and earlier). This can be achieved with scr=T.

delmod replaces the functionality of the older clearcal task. If one still decides to use the MODEL_DATA columns, however, clearcal is still useful and will reset both the MODEL_DATA and CORRECTED_DATA columns to unity:

CASA <11>: inp clearcal
---------> inp(clearcal)
#  clearcal :: Re-initializes the calibration for a visibility data set
vis                 =         ’’        #  Name of input visibility file (MS)
field               =         ’’        #  Select field using field id(s) or field name(s)
spw                 =         ’’        #  Select spectral window/channel.
intent              =         ’’        #  Select observing intent

with field, spw, and intent being data selection parameters. With the introduction of the on-the-fly calculation of the MODEL visibilities, and the fact that applycal overwrites any previously existing CORRECTED_DATA column, clearcal is not required anymore unless usescratch=True is chosen in calibration tasks, and it is also not recommended to use clearcal to create the scratch columns at the beginning of data calibration; all benefits from the on-the-fly model would be made obsolete.

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