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NRAO Home > CASA > CASA Task Reference Manual |
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0.1.76 mstransform
Requires:
Synopsis
Split the MS, combine/separate/regrid spws and do channel and time
averaging
Description
The task mstransform can do the same functionalities available in cvel,
partition, hanningsmooth and split without the need to read and write the
output to disk multiple times. The main features of this task are:
* take an input MS or Multi-MS (MMS) * ability to create an output MS or MMS * spw combination and separation * channel averaging taking flags and weights into account * time averaging taking flags and weights into account * reference frame transformation * Hanning smoothing
All these transformations will be applied on the fly without any writing to disk to optimize I/O. The user can ask to create a Multi-MS in parallel using CASA’s cluster infrastructure using the parameter createmms. See MPIInterface for more information on the cluster infrastructure.
This task is implemented in a modular way to preserve the functionalities available in the replaced tasks. One can choose which functionality to apply or apply all of them by setting the corresponding parameters to True. Note that there is an order in which the transformations are applied to the data that makes logical sense on the point of view of the data analysis.
This task can create a multi-MS as the output. 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. It can also be used to create a normal MS, split-based on the given data selection parameters.
The mstransform task creates a Multi-MS in parallel, using the CASA MPI framework. The user should start CASA as follows in order to run it in parallel.
1) Start CASA on a single node with 8 engines. The first engine will be used as the MPIClient, where the user will see the CASA prompt. All other engines will be used as MPIServers and will process the data in parallel. mpicasa -n 8 casa –nogui –log2term mstransform(.....)
2) Running on a group of nodes in a cluster. mpicasa -hostfile user_hostfile casa .... mstransform(.....)
where user_hostfile contains the names of the nodes and the number of engines to use in each one of them. Example: pc001234a, slots=5 pc001234b, slots=4
If CASA is started without mpicasa, it is still possible to create an MMS, but the processing will be done in sequential.
The resulting WEIGHT_SPECTRUM produced by mstransform is in the statistical sense correct for the simple cases of channel average and time average, but not for the general re-gridding case, in which the error propagation formulas applicable for WEIGHT_SPECTRUM are yet to be defined. Currently, as in cvel and in the imager, WEIGHT_SPECTRUM is transformed in the same way as the other data columns. Notice that this is not formally correct from the statistical point of view, but is a good approximation at this stage.
NOTE: the input/output in mstransform have a one-to-one relation. input MS – output MS input MMS – output MMS
unless the user sets the parameter createmms to True to create the following: input MS – output MMS
Arguments
Inputs |
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vis |
| Name of input Measurement set or Multi-MS.
| |
| allowed: | string |
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| Default: |
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outputvis |
| Name of output Measurement Set or Multi-MS.
| |
| allowed: | string |
|
| Default: |
| |
createmms |
| Create a multi-MS output from an input MS.
| |
| allowed: | bool | |
| Default: | False |
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separationaxis |
| Axis to do parallelization
across(scan,spw,auto,baseline).
| |
| allowed: | string |
|
| Default: | auto |
|
numsubms |
| The number of Sub-MSs to create (auto or any number)
| |
| allowed: | any |
|
| Default: | variant auto | |
tileshape |
| List with 1 or 3 elements giving the tile shape of the disk
data columns. | |
| allowed: | intArray |
|
| Default: | 0 |
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field |
| Select field using ID(s) or name(s).
| |
| allowed: | any |
|
| Default: | variant
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spw |
| Select spectral window/channels.
| |
| allowed: | any |
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| Default: | variant
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scan |
| Select data by scan numbers.
| |
| allowed: | any |
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| Default: | variant
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antenna |
| Select data based on antenna/baseline.
| |
| allowed: | any |
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| Default: | variant
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correlation |
| Correlation: ” ==> all, correlation=”XX,YY”.
| |
| allowed: | any |
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| Default: | variant
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timerange |
| Select data by time range.
| |
| allowed: | any |
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| Default: | variant
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intent |
| Select data by scan intent.
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| allowed: | any |
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| Default: | variant
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array |
| Select (sub)array(s) by array ID number.
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| allowed: | any |
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| Default: | variant
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uvrange |
| Select data by baseline length.
| |
| allowed: | any |
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| Default: | variant
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observation |
| Select by observation ID(s).
| |
| allowed: | any |
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| Default: | variant
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feed |
| Multi-feed numbers: Not yet implemented.
| |
| allowed: | any |
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| Default: | variant
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datacolumn |
| Which data column(s) to process.
| |
| allowed: | string |
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| Default: | corrected | |
realmodelcol |
| Make real a virtual MODEL column.
| |
| allowed: | bool | |
| Default: | False |
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keepflags |
| Keep *completely flagged rows* or drop them from the
output.
| |
| allowed: | bool | |
| Default: | True |
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usewtspectrum |
| Create a WEIGHT_SPECTRUM column in the output
MS. | |
| allowed: | bool |
|
| Default: | False | |
combinespws |
| Combine the input spws into a new output spw. Only
supported when the number of channels is the same for
all the spws.
| |
| allowed: | bool | |
| Default: | False |
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chanaverage |
| Average data in channels.
| |
| allowed: | bool | |
| Default: | False |
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chanbin |
| Width (bin) of input channels to average to form an
output channel.
| |
| allowed: | any |
|
| Default: | variant 1 | |
hanning |
| Hanning smooth data to remove Gibbs ringing.
| |
| allowed: | bool | |
| Default: | False |
|
regridms |
| Transform channel labels and visibilities to a different
spectral reference frame. Notice that u,v,w data is not
transformed.
| |
| allowed: | bool |
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| Default: | False |
|
mode |
| Regridding mode
(channel/velocity/frequency/channel_b).
| |
| allowed: | string |
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| Default: | channel |
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nchan |
| Number of channels in the output spw (-1=all).
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| allowed: | int |
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| Default: | -1 |
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start |
| First channel to use in the output spw
(mode-dependant)
| |
| allowed: | any |
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| Default: | variant 0 |
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width |
| Number of input channels that are used to create an
output channel.
| |
| allowed: | any |
|
| Default: | variant 1 |
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nspw |
| Number of output spws to create in output MS.
| |
| allowed: | int |
|
| Default: | 1 |
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interpolation |
| Spectral interpolation method.
| |
| allowed: | string |
|
| Default: | linear |
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phasecenter |
| Phase center direction to be used for the spectral
coordinate transformation: position or field index
| |
| allowed: | any |
|
| Default: | variant
|
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restfreq |
| Rest frequency to use for output.
| |
| allowed: | string |
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| Default: |
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outframe |
| Output reference frame (”=keep input frame).
| |
| allowed: | string |
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| Default: |
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veltype |
| Velocity definition.
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| allowed: | string |
|
| Default: | radio |
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timeaverage |
| Average data in time.
| |
| allowed: | bool |
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| Default: | False |
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timebin |
| Bin width for time averaging.
| |
| allowed: | string |
|
| Default: | 0s |
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timespan |
| Span the timebin across scan, state or both.
| |
| allowed: | any |
|
| Default: | variant
|
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maxuvwdistance |
| Maximum separation of start-to-end baselines that can
be included in an average. (meters)
| |
| allowed: | double |
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| Default: | 0.0 |
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docallib |
| Enable on-the-fly (OTF) calibration as in task applycal
| |
| allowed: | bool |
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| Default: | False |
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callib |
| Path to calibration library file
| |
| allowed: | string |
|
| Default: |
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douvcontsub |
| Enable continuum subtraction as in task uvcontsub
| |
| allowed: | bool |
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| Default: | False |
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fitspw |
| Spectral window:channel selection for fitting the
continuum
| |
| allowed: | string |
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| Default: |
|
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fitorder |
| Polynomial order for the fits
| |
| allowed: | int |
|
| Default: | 0 |
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want_cont |
| Produce continuum estimate instead of continuum
subtracted data
| |
| allowed: | bool |
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| Default: | False |
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denoising_lib |
| Use new denoising library (based on GSL) instead of
casacore fitting routines
| |
| allowed: | bool |
|
| Default: | True |
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nthreads |
| Number of OMP threads to use (currently maximum
limited by number of polarizations)
| |
| allowed: | int |
|
| Default: | 1 |
|
niter |
| Number of iterations for re-weighted linear fit
| |
| allowed: | int |
|
| Default: | 1 |
|
disableparallel |
| Hidden parameter for internal use only. Do not change
it!
| |
| allowed: | bool |
|
| Default: | False |
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ddistart |
| Hidden parameter for internal use only. Do not change
it!
| |
| allowed: | int |
|
| Default: | -1 |
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taql |
| Table query for nested selections
| |
| allowed: | string |
|
| Default: |
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monolithic_processing |
| Hidden parameter for internal use only. Do not change
it!
| |
| allowed: | bool |
|
| Default: | False |
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reindex |
| Hidden parameter for use in the pipeline context only
| |
| allowed: | bool |
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| Default: | True |
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Detailed description of keyword arguments:
--- Input/Output parameters ---
vis -- Name of input visibility file
default: ’’; example: vis=’ngc5921.ms’
outputvis -- Name of output visibility file or Multi-MS
default: ’’; example: outputvis=’ngc5921.mms’
createmms -- Create an output Multi-MS from an input MS.
default: False
This parameter only has effect if set to True, when it will try
to create an output Multi-MS from an input MS. The one-to-one
relation of input/output in mstransform is:
input MS -- output MS
input MMS -- output MMS
by setting createmms=True, the following is possible:
input MS -- output MMS
NOTE: See information on processing input Multi-MS at the end of this help section.
separationaxis -- Axis to do parallelization across.
default: ’auto’
options: ’scan’, ’spw’, ’auto’, ’baseline’
* The ’auto’ option will partition per scan/spw to obtain optimal load balancing with the
following criteria:
1 - Maximize the scan/spw/field distribution across sub-MSs
2 - Generate sub-MSs with similar size
* The ’scan’ or ’spw’ axes will partition the MS into scan or spw. The individual sub-MSs may
not be balanced with respect to the number of rows.
* The ’baseline’ axis is mostly useful for Single-Dish data. This axis will partition the MS
based on the available baselines. If the user wants only auto-correlations, use the
antenna selection such as antenna=’*&&&’ together with this separation axis. Note that in
if numsubms=’auto’, partition will try to create as many subMSs as the number of available
servers in the cluster. If the user wants to have one subMS for each baseline, set the numsubms
parameter to a number higher than the number of baselines to achieve this.
numsubms -- The number of sub-MSs to create.
default: ’auto’
Options: any integer number (example: numsubms=4)
The default ’auto’ is to partition using the number of available servers in the cluster.
If the task is unable to determine the number of running servers, or the user did not start CASA
using mpicasa, numsubms will use 8 as the default.
tileshape -- List with 1 or 3 elements describing the tile shape that will be used
to save the columns to disk. (list)
default: [0]
options: [0] or [1] or [int,int,int]. When list has only one element, it should
be either 0 or 1. When the list has three elements, they should be the
number of correlations, channels, rows.
--- Data selection parameters ---
field -- Select field using field id(s) or field name(s).
[run listobs to obtain the list iof d’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.
NOTE: mstransform does not support multiple channel ranges per
spectral window (’;’).
scan -- Scan number range
default: ’’=all
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.
correlation -- Correlation types or expression.
default: ’’ (all correlations)
example: correlation=’XX,YY’
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
observation -- Select by observation ID(s)
default: ’’=all
feed -- Selection based on the feed - NOT IMPLEMENTED YET
default: ’’=all
datacolumn -- Which data column to use for processing (case-insensitive).
default: ’corrected’; example: datacolumn=’data’
options: ’data’, ’model’, ’corrected’, ’all’,’float_data’, ’lag_data’,
’float_data,data’, ’lag_data,data’.
NOTE: ’all’ = whichever of the above that are present. If the requested
column does not exist, the task will exit with an error.
When datacolumn is set to either one of the values ’model’,’all’,
’data,model,corrected’, a sub-parameter realmodelcol will be enabled.
See description below.
realmodelcol -- Make real a virtual MODEL column. If set to True, a real MODEL_DATA
column will be added to the output MS based on the existing SOURCE_MODEL
column.
default: False
keepflags -- Keep completely flagged rows in the output or drop them. This has no
effect on 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.
IMPORTANT: Regardless of this parameter, flagged data is never included in
channel averaging. On the other hand, partially flagged rows will
always be included in time averaging. The average value of the
flagged data for averages containing ONLY flagged data in the relevant
output channel will be written to the output with the corresponding
flag set to True, while only unflagged data is used on averages where
there is some unflagged data with the flag set to False.
default: True (keep completely flagged rows in the output)
usewtspectrum -- Create a WEIGHT_SPECTRUM column in the output MS. When set to True,
a WEIGHT_SPECTRUM column will be created using the input WEIGHT column,
such that each channel in the WEIGHT_SPECTRUM will get WEIGHT/nChannels.
default: False
--- SPW combination parameters ---
combinespws -- Combine the input spws into a new output spw.
default: False
NOTE: This option is only supported when the number of channels is the same for
all the spws. Using this option with different numbers of channels for
different spws will result in an error.
NOTE: Whenever the data to be combined has different EXPOSURE values
in the spectral windows, mstransform will use the WEIGHT_SPECTRUM
for the combination. If WEIGHT_SPECTRUM is not available, it will
use the values from the WEIGHT column. Each output channel is calculated
using the following equation:
outputChannel_j = SUM(inputChannel_i*contributionFraction_i*inputWeightSpectrum_i)
------------------------------------------------------------------
SUM(contributionFraction_i*inputWeightSpectrum_i)
--- Channel averaging parameters ---
chanaverage -- Average data across channels. Partially flagged data is not be included in the average
unless all data contributing to a given output channel is flagged. In this case,
mstransform calculates the average of all flagged data, and writes it to the output MS
with the corresponding flag set to true. If present, WEIGHT_SPECTRUM/SIGMA_SPECTRUM
are used together with the channelized flags (FLAG), to compute a weighted average
(using WEIGHT_SPECTRUM for CORRECTED_DATA and SIGMA_SPECTRUM for DATA).
default: False
chanbin -- Bin width for channel average in number of input channels.
If a list is given, each bin applies to one of the selected SPWs.
default: 1 => no channel averaging.
options: (int) or [int]
example: chanbin=[2,3] => average 2 channels of 1st selected
spectral window and 3 in the second one.
NOTE: WEIGHT_SPECTRUM/SIGMA_SPECTRUM will be used (if present) in
addition to the flags to compute a weighted average. The calculations
is done as follows:
1) When WEIGHT_SPECTRUM/SIGMA_SPECTRUM are not present:
Avg = SUM(Chan_i*Flag_i)/SUM(Flag_i)
2) When WEIGHT_SPECTRUM/SIGMA_SPECTRUM are present:
Avg = SUM(Chan_i*Flag_i*WeightSpectrum_i)/SUM(Flag_i*WeightSpectrum_i)
--- Hanning smoothing parameters ---
hanning -- Hanning smooth frequency channel data to remove Gibbs ringing.
default: False
--- Regrid parameters ---
regridms -- Transform channel labels and visibilities to a different spectral reference frame.
Notice that u,v,w data is not transformed.
default: False
mode -- Regridding mode.
default: ’channel’; produces equidistant grid based on first selected channel.
options: ’velocity’, ’frequency’, ’channel_b’.
When set to velocity or frequency, it means that the channels must be specified
in the respective units. When set to channel_b it means an alternative ’channel’
mode that does not force an equidistant grid. It is faster.
nchan -- Number of channels in the output spw (int).
default: -1
start -- First channel to use in the output spw (depends on the mode)
default: 0 --> when mode=’channel’
When mode=’channel’, ’start’ means the first channel in the input spw
to use when creating the output spw. When mode=’frequency’,
’start’ means the lowest frequency of the output spw. If this information
is not available, leave it blank and mstransform will calculate it.
width -- Width of input channels that are used to create an output channel.
default: 1
Note that mstransform will only shift spws with channel widths of the same
sign in a single operation. If you are regridding spws with mixed positive
and negative channel widths, you should run this task separated for each
group of spws. You can verify the channel widths for your MS using
listobs for example, and looking at the SPW table, column ChanWid.
nspw -- Number of output spws to create in the output MS/MMS (int).
default: 1 --> it means, do not separate the spws.
One can regrid the MS or not and further separate the
output into a given number of spws. Internally, the framework
will combine the selected spws before separating them so that
channel gaps and overlaps are taken into account. This parameter
will create a regular grid of spws in the output MS. If nchan
is set, it will refer to the number of output channels in each
of the separated spws.
interpolation -- Spectral interpolation method.
default: ’linear’
options: ’nearest’, ’cubic’, ’spline’, ’fftshift’
phasecenter -- Direction measure or fieldid. To be used in mosaics to indicate
the center direction to be used in the spectral coordinate transformation.
default: ’’ (first selected field)
options: FIELD_ID (int) or center coordinate measure (str).
example: phasecenter=6 or phasecenter=’J2000 19h30m00 -40d00m00’
restfreq -- Specify rest frequency to use for output.
default: ’’; occasionally it is necessary to set this.
example1 for some VLA spectral line data.
example2 for NH_3 (1,1) put restfreq=’23.694496GHz’.
outframe -- Output reference frame (case-insensitive).
default: ’’; it will keep the input reference frame.
options: ’LSRK’, ’LSRD’, ’BARY’, ’GALACTO’, ’LGROUP’, ’CMB’, ’GEO’, ’TOPO’.
veltype -- Definition of velocity (as used in mode).
default: ’radio’
--- Time averaging parameters ---
timeaverage -- Average data across time. Partially flagged data is not be included in the average
unless all data contributing to a given output channel is flagged. In this case,
mstransform calculates the average of all flagged data, and writes it to the output MS
with the corresponding flag set to true. If keepflags=False, the fully flagged data
is not be written to the output MS. If present, WEIGHT_SPECTRUM/SIGMA_SPECTRUM
are used together with the channelized flags (FLAG), to compute a weighted average
(using WEIGHT_SPECTRUM for CORRECTED_DATA and SIGMA_SPECTRUM for DATA). Otherwise
WEIGHT/SIGMA are used instead to average together data from different integrations.
default: False
timebin -- Bin width for time average in seconds.
default: ’0s’
timespan -- Let the timebin span across scan, state or both.
State is equivalent to sub-scans. One scan may have several
state ids. For ALMA MSs, the sub-scans are limited to about
30s duration each. In these cases, the task will automatically
add state to the timespan parameter. To see the number of states
in an MS, use the msmd tool. See help msmd.
default: ’’ (separate time bins by both of the above)
options: ’scan’, ’state’, ’state,scan’
examples:
timespan = ’scan’; can be useful when the scan number
goes up with each integration as in many WSRT MSs.
timespan = [’scan’, ’state’]: disregard scan and state
numbers when time averaging.
timespan = ’state,scan’; same as above.
maxuvwdistance -- Provide a maximum separation of start-to-end baselines
that can be included in an average. (int)
default: 0.0 (given in meters)
--- On-the-fly calibration parameters ---
docallib -- Enable on-the-fly (OTF) calibration as in task applycal
default: False
callib -- Path to calibration library file, which is a ascii file containing
the parameters to correct the data as task in task applycal, namely
gaintable/gainfield/interp/spwmap/calwt. In a Cal Library file, each
row expresses the calibration apply instructions for a particular
caltable and (optionally) a specific selection of data in the MS to
which it is to be applied.
default: ’’ (there is no default callib file)
examples:
caltable=’cal.G’ tinterp=’linear’ calwt=True
-> Arrange a caltable called cal.G to be applied (with no detailed selection)
to all MS data with linear interpolation in time, and with the weights also
calibrated.
caltable=’cal.G’ tinterp=’linear’ fldmap=’nearest’ spwmap=[0,1,1,3] calwt=True
caltable=’cal.B’ finterp=’linear’ fldmap=’3’ spwmap=[0,0,0,0] calwt=False
-> In this case, solutions from cal.G will be selected based on directional
proximity (’nearest’) for each MS field via the fldmap parameter, and spw 2
will be calibrated by spw 1 solutions. For cal.B, solutions from field id 3
will be used exclusively, with spw 0 calibrating all MS spws.
------ Multi-MS Processing and Heuristics ---------
** Input Multi-MS (MMS) **
Task mstransform will process an input MMS in parallel whenever possible. Each sub-MS of
the MMS will be processed in a separate engine and the results will be post-processed at the
end to create an output MMS. The output MMS will have the same separationaxis of the input
MMS, which will be written to the table.info file inside the MMS directory.
Naturally, some transformations available in mstransform require more care when the user
first partition the MS. If one wants to do a combination of spws by setting the parameter
combinespws = True in mstransform, the input MMS needs to contain all the
selected spws in each of the sub-MSs or the processing will fail. For this, one may set the initial
separationaxis to scan or use the default auto with a proper numsubms set so that each sub- MS in
the MMS is self-contained with all the necessary spws for the combination.
The task will check if the sub-MSs contain all the selected spws when combinespws=True
and if not, it will issue a warning and process the input MMS as a monolithic MS. In this
case, the separation axis of the output MMS will be set to scan, regardless of what the input
axis was.
A similar case happens when the separation axis of the input MMS is per scan and the user
asks to do time averaging with time spanning across scans. If the individual sub-MSs are not
self-contained of the necessary scans and the duration of the scans is shorter than the given
timebin, the spanning will not be possible. In this case, the task will process the input MMS as
a monolithic MS and will set the axis of the output MMS to spw.
It is important that the user sets the separation axis correctly when first partitioning the MS.
See the table below for when it is possible to process the input MMS in parallel or not, using
mstransform.
input MMS axis combinespws=True nspw > 1 timeaverage=True, timespan=’scan’
-------------------------------------------------------------------------------
scan YES YES NO
spw NO NO YES
auto MAYBE MAYBE MAYBE
------ EXAMPLES ------
More documentation on mstransform can be found here:
http://www.eso.org/~scastro/ALMA/casa/MST/MSTransformDocs/MSTransformDocs.html
1) Split out a single channel.
mstransform(vis=’ctb80-vsm.ms’, outputvis=’mychn.ms’, datacolumn=’data’, spw=’0:25’)
2) Only combine the selected spws into a single output spw.
mstransform(vis=’Four_ants.ms’, outputvis=’myspw.ms’, combinespws=True, spw=’0~3’)
3) Combine two spws and regrid one field, using two input channels to make one output.
mstransform(vis=’jupiter6cm.demo.ms’,outputvis=’test1.ms’,datacolumn=’DATA’,field=’11’,
spw=’0,1’, combinespws=True, regridms=True, nchan=1, width=2)
4) Combine 24 spws and regrid in frequency mode to create 21 output channels. Change the
phase center.
mstransform(vis=’g19_d2usb_targets_line.ms’, outputvis=’test2.ms’, datacolumn=’DATA’,
combinespws=True, regridms=True, mode=’frequency’, nchan=21, start=’229587.0MHz’,
width=’1600kHz’, phasecenter="J2000 18h25m56.09 -12d04m28.20")
5) Only apply Hanning smoothing to MS.
mstransform(vis=’g19_d2usb_targets_line.ms’, outputvis=’test3.ms’, datacolumn=’DATA’,
hanning=True)
6) Change the reference frame and apply Hanning smoothing after combining all spws.
mstransform(vis=’g19_d2usb_targets_line.ms’, outputvis=’test4.ms’, datacolumn=’DATA’,
combinespws=True, regridms=True, mode="channel", outframe="BARY",
phasecenter="J2000 18h25m56.09 -12d04m28.20", hanning = True)
7) Apply time averaging using a bin of 30 seconds on the default CORRECTED column.
mstransform(vis=’g19_d2usb_targets_line.ms’, outputvis=’test5.ms’, timeaverage=True,
timebin=’30s’)
8) Apply OTF calibration to ng5921 using a calibration library
mstransform(vis=’ngc5921.ms’, outputvis=’ngc5921_calibrated.ms’,docallib=True,
callib=’unittest/mstransform/ngc5921_regression/ngc5921_callib.txt’)
More information about CASA may be found at the
CASA web page
Copyright © 2016 Associated Universities Inc., Washington, D.C.
This code is available under the terms of the GNU General Public Lincense
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