Description

| Oldsplit is the general purpose program to make a new data set that is a
| subset or averaged form of an existing data set. General selection
| parameters are included, and one or all of the various data columns
| (DATA, LAG_DATA and/or FLOAT_DATA, and possibly MODEL_DATA and/or
| CORRECTED_DATA) can be selected.
|
| Oldsplit is often used after the initial calibration of the data to make a
| smaller measurement set with only the data that will be used in
| further flagging, imaging and/or self-calibration. Oldsplit can
| average over frequency (channels) and time (integrations).

  | Keyword arguments:
| vis -- Name of input visibility file
| default: none; example: vis='ngc5921.ms'

| outputvis -- Name of output visibility file
| default: none; example: outputvis='ngc5921_src.ms'
|
| datacolumn -- Which data column to split out
| default='corrected'; example: datacolumn='data'
| Options: 'data', 'model', 'corrected', 'all',
| 'float_data', 'lag_data', 'float_data,data', and
| 'lag_data,data'.
| N.B.: 'all' = whichever of the above that are present.
| Otherwise the selected column will go to DATA (or
| FLOAT_DATA) in the output.
| Splitting with the default datacolumn='corrected'
| before clean is normally required for self-calibration!
|
| --- Data Selection (see help par.selectdata for more detailed
| information)

| | field -- Select field using field id(s) or field name(s).
| [run listobs to obtain the list id's or names]
| default: ''=all fields If field string is a non-negative
| integer, it is assumed to be a field index
| otherwise, it is assumed to be a field name
| field='0~2'; field ids 0,1,2
| field='0,4,5~7'; field ids 0,4,5,6,7
| field='3C286,3C295'; fields named 3C286 and 3C295
| field = '3,4C*'; field id 3, all names starting with 4C

| spw -- Select spectral window/channels
| default: ''=all spectral windows and channels
| spw='0~2,4'; spectral windows 0,1,2,4 (all channels)
| spw='<2'; spectral windows less than 2 (i.e. 0,1)
| spw='0:5~61'; spw 0, channels 5 to 61
| spw='0,10,3:3~45'; spw 0,10 all channels, spw 3 - chans 3 to 45.
| spw='0~2:2~6'; spw 0,1,2 with channels 2 through 6 in each.
| spw = '*:3~64' channels 3 through 64 for all sp id's
| spw = ' :3~64' will NOT work.
| Oldsplit does not support multiple channel ranges per spectral
| window (';') because it is not clear whether to keep the ranges
| in the original spectral window or make a new spectral window
| for each additional range.

| width -- Defines the number of channel to average to form the one
| output channel.
| default: '1' => no channel averaging
| example: width=[2,3] => average 2 channels of 1st
| spectral window selected and 3 in the second one.

| antenna -- Select data based on antenna/baseline
| default: '' (all)
| Non-negative integers are assumed to be antenna indices, and
| anything else is taken as an antenna name.
|
| Examples:
| antenna='5&6': baseline between antenna index 5 and index 6.
| antenna='VA05&VA06': baseline between VLA antenna 5 and 6.
| antenna='5&6;7&8': baselines 5-6 and 7-8
| antenna='5': all baselines with antenna 5
| antenna='5,6,10': all baselines including antennas 5, 6, or 10
| antenna='5,6,10&': all baselines with *only* antennas 5, 6, or
| 10. (cross-correlations only. Use &&
| to include autocorrelations, and &&&
| to get only autocorrelations.)
| antenna='!ea03,ea12,ea17': all baselines except those that
| include EVLA antennas ea03, ea12, or
| ea17.

| timebin -- Interval width for time averaging.
| default: '0s' or '-1s' (no averaging)
| example: timebin='30s'
| '10' means '10s'

| timerange -- Select data based on time range:
| default = '' (all); examples,
| timerange = 'YYYY/MM/DD/hh:mm:ss~YYYY/MM/DD/hh:mm:ss'
| Note: if YYYY/MM/DD is missing date, timerange defaults to the
| first day in the dataset
| timerange='09:14:0~09:54:0' picks 40 min on first day
| timerange='25:00:00~27:30:00' picks 1 hr to 3 hr 30min
| on next day
| timerange='09:44:00' data within one integration of time
| timerange='>10:24:00' data after this time

| array -- (Sub)array number range
| default: ''=all

| uvrange -- Select data within uvrange (default units meters)
| default: ''=all; example:
| uvrange='0~1000klambda'; uvrange from 0-1000 kilo-lambda
| uvrange='>4klambda';uvranges greater than 4 kilo-lambda
| uvrange='0~1000km'; uvrange in kilometers

| scan -- Scan number range
| default: ''=all

| intent -- Select by scan intent (state). Case sensitive.
| default: '' = all
| Examples:
| intent = 'CALIBRATE_ATMOSPHERE_REFERENCE'
| intent = 'calibrate_atmosphere_reference'.upper() # same as above
| # Select states that include one or both of CALIBRATE_WVR.REFERENCE
| # or OBSERVE_TARGET_ON_SOURCE.
| intent = 'CALIBRATE_WVR.REFERENCE, OBSERVE_TARGET_ON_SOURCE'

| correlation -- Select correlations, e.g. 'rr, ll' or ['XY', 'YX'].
| default '' (all).

| observation -- Select by observation ID(s).
| default: '' = all

| combine -- Let time bins span changes in scan and/or state.
| default = '' (separate time bins by both of the above)
| combine = 'scan': Can be useful when the scan number
| goes up with each integration,
| as in many WSRT MSes.
| combine = ['scan', 'state']: disregard scan and state
| numbers when time averaging.
| combine = 'state,scan': Same as above.

| keepflags -- If practical, keep completely flagged rows instead of
| dropping them. This has absolutely no effect on averaging
| calculations, or partially flagged rows. All of the
| channels and correlations of a row must be flagged for it
| to be droppable, and a row must be well defined to be
| keepable. The latter condition means that this option has
| no effect on time averaging - in that case fully flagged
| rows are automatically omitted. Regardless of this
| parameter, flagged data is never included in averaging
| calculations.
|
| The only time keepflags matters is if
| 1. the input MS has some completely flagged rows
| and
| 2. time averaging is not being done.
|
| Then, if keepflags is False, the completely flagged rows
| will be omitted from the output MS. Otherwise, they will
| be included (subject to the selection parameters).
|

| keepmms -- If true and the input is a multi-MS, make the output one, too.
| Otherwise, the output will be a normal MS without partitioning.
| (experimental)
| Default: False