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| == Help on concat task:==
| | {{concat}} |
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| <pre>
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| Concatenate several visibility data sets.
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| The list of data sets given in the vis argument are concatenated into an output
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| data set in concatvis. If concatvis already exists (e.g., it is the same as the
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| first input data set), then the other input data sets will be appended to the
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| concatvis data set. There is no limit to the number of input data sets.
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| If none of the input data sets have any scratch columns (model and corrected
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| columns), none are created in the concatvis. Otherwise these columns are
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| created on output and initialized to their default value (1 in model column,
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| data in corrected column) for those data with no input columns.
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| Spectral windows for each data set with the same chanelization, and within a
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| specified frequency tolerance of another data set will be combined into one
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| spectral window.
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| A field position in one data set that is within a specified direction tolerance
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| of another field position in any other data set will be combined into one
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| field. The field names need not be the same---only their position is used.
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| Keyword arguments:
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| vis -- Name of input visibility files to be combined
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| default: none; example: vis = 'mydata.ms',
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| vis=['src2.ms','ngc5921.ms','ngc315.ms']
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| concatvis -- Name of visibility file that will contain the concatenated data
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| note: if this file exits on disk then the input files are
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| added to this file. Otherwise the new file contains
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| the concatenated data. Be careful here when concatenating to
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| an existing file.
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| default: none; example: concatvis='src2.ms'
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| example: concatvis='outvis.ms'
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| other examples:
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| concat(vis=['src2.ms','ngc5921.ms'], concatvis='src2.ms')
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| will concatenate 'ngc5921.ms' into 'src2.ms', and the original
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| src2.ms is lost
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| concat(vis=['src2.ms','ngc5921.ms'], concatvis='out.ms')
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| will concatenate 'ngc5921.ms' and 'src2.ms' into a file named
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| 'out.ms'; the original 'ngc5921.ms' and 'src2.ms' are untouched.
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| concat(vis=['v1.ms','v2.ms'], concatvis = 'vall.ms')
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| then
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| concat(vis=['v3.ms','v4.ms'], concatvis = 'vall.ms')
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| vall.ms will contains v1.ms+v2.ms+v3.ms+v4.ms
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| Note: run flagmanager to save flags in the concatvis
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| freqtol -- Frequency shift tolerance for considering data to be in the same
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| spwid. The number of channels must also be the same.
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| default: '' do not combine unless frequencies are equal
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| example: freqtol='10MHz' will not combine spwid unless they are
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| within 10 MHz.
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| Note: This option is useful to conbine spectral windows with very slight
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| frequency differences caused by Doppler tracking, for example.
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| dirtol -- Direction shift tolerance for considering data as the same field
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| default: '' means always combine.
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| example: dirtol='1.arcsec' will not combine data for a field unless
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| their phase center differ by less than 1 arcsec. If the field names
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| are different in the input data sets, the name in the output data
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| set will be the first relevant data set in the list.
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| timesort -- If true, the output visibility table will be sorted in time.
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| default: false. Data in order as read in.
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| example: timesort=true
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| Note: There is no constraint on data that is simultaneously observed for
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| more than one field; for example multi-source correlation of VLBA data.
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| </pre>
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