2.4.1.0 simulator.open

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simulator.open - Function

2.4.1 Construct a simulator tool and create a new MeasurementSet

Description

A simulator tool can either operate on an existing MeasurementSet, predicting and/or corrupting data on the existing uvw coordinates

– to do that open the MS with sm.openfromms(msname).

or it can be used to create a new MeasurementSet from descriptions of the array configuration and the observational parameters

– to create a new MS, use this method sm.open(msname).

You will also need to run setconfig, setfield, setspw, setspwindow, setfeed, and settimes.

Creating the actual (empty) MS is accomplished with sm.observe. Data can be subsequently sm.predict-ed and sm.corrupt-ed.

NOTE: sm.predict assumes the model image units are Jy/pixel, and in fact will overwrite the brightness units of the image itself!

Arguments


Inputs
ms	MeasurementSet to be created
	allowed:	string
	Default:

Returns
bool

Example

    In this example, we read in the antenna coordinates from an ASCII file,
    and simulate a single-pointing VLA observation with a calibrator.
    Note that no primary beam attenuation will be applied (see sm.setvp).

    tabname = ’VLAC.LOCAL.TAB’
    asciifile = ’VLAC.LOCAL.STN’
    mytab=table.create()
    mytab.fromascii(tabname, asciifile);
    xx=[]; yy:=[]; zz:=[]; diam:=[];
    xx = mytab.getcol(’X’);
    yy = mytab.getcol(’Y’);
    zz = mytab.getcol(’Z’);
    diam = mytab.getcol(’DIAM’);
    #
    sm.open(’NEW1.ms’)
    # do configuration
    posvla = me.observatory(’vla’);  #  me.observatory(’ALMA’) also works!
    sm.setconfig(telescopename=’VLA’, x=xx, y=yy, z=zz, dishdiameter=diam,
         mount=’alt-az’, antname=’VLA’,
                 coordsystem=’local’, referencelocation=posvla);

    # Initialize the spectral windows
    sm.setspwindow(spwname=’CBand’, freq=’5GHz’,
   deltafreq=’50MHz’,
   freqresolution=’50MHz’,
   nchannels=1,
   stokes=’RR RL LR LL’);
    sm.setspwindow(spwname=’LBand’, freq=’1.420GHz’,
   deltafreq=’3.2MHz’,
   freqresolution=’3.2MHz’,
   nchannels=32,
   stokes=’RR LL’);

    # Initialize the source and calibrater
    sm.setfield(sourcename=’My cal’,
sourcedirection=[’J2000’,’00h0m0.0’,’+45.0.0.000’],
calcode=’A’);
    sm.setfield(sourcename=’My source’,
sourcedirection=[’J2000’,’01h0m0.0’,’+47.0.0.000’]);

    sm.setlimits(shadowlimit=0.001, elevationlimit=’8.0deg’);
    sm.setauto(autocorrwt=0.0);

    sm.settimes(integrationtime=’10s’, usehourangle=F,
                referencetime=me.epoch(’utc’, ’today’));

    sm.observe(’My cal’, ’LBand’, starttime=’0s’, stoptime=’300s’);
    sm.observe(’My source’, ’LBand’, starttime=’310s’, stoptime=’720s’);
    sm.observe(’My cal’, ’CBand’, starttime=’720s’, stoptime=’1020s’);
    sm.observe(’My source’, ’CBand’, starttime=’1030s’, stoptime=’1500s’);

    sm.setdata(spwid=1, fieldid=1);
    sm.predict(imagename=’M31.MOD’);
    sm.setdata(spwid=2, fieldid=2);
    sm.predict(imagename=’BigLBand.MOD’);
    sm.close();

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