2.4.1.0 simulator.open

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simulator.open - Function

2.4.1 Construct a simulator tool and creating a new MeasurementSet

Description

This is used to construct simulator tools. A simulator tool can either be instantiated from an existing MeasurementSet, predicting and/or corrupting data on the given coordinates, or it can be used to create a fundamentally new MeasurementSet from descriptions of the array configuration and the observational parameters. This is useful for making a simulator tool which will make a MeasurementSet from scratch. In order to do this, you must also run setconfig, setfield, setspwindow, setfeed, and settimes. Creating the actual MS is performed by observe. Data can be predict-ed and then corrupted-ed. NOTE: sm.predict assumes the model image units are Jy/pixel, and in fact will overwrite the brightness units of the image itself! In this example, we read in the antenna coordinates from an ASCII file:

Arguments


Inputs
ms	MeasurementSet to be created
	allowed:	string
	Default:

Returns
bool

Example

    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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