Example #1
0
 def setUp(self):
     self.dir = './test_results'
     os.makedirs(self.dir, exist_ok=True)
     self.lowcore = create_named_configuration('LOWBD2-CORE')
     self.times = (numpy.pi / (12.0)) * numpy.linspace(-3.0, 3.0, 7)
     self.frequency = numpy.array([1e8])
     self.channel_bandwidth = numpy.array([1e6])
     self.phasecentre = SkyCoord(ra=+180.0 * u.deg, dec=-60.0 * u.deg, frame='icrs', equinox=2000.0)
     self.vis = create_visibility(self.lowcore, self.times, self.frequency,
                                  channel_bandwidth=self.channel_bandwidth,
                                  phasecentre=self.phasecentre, weight=1.0,
                                  polarisation_frame=PolarisationFrame('stokesI'))
     self.vis.data['vis'] *= 0.0
     
     # Create model
     self.test_model = create_test_image(cellsize=0.001, phasecentre=self.vis.phasecentre,
                                         frequency=self.frequency)
     self.vis = predict_2d(self.vis, self.test_model)
     assert numpy.max(numpy.abs(self.vis.vis)) > 0.0
     self.model = create_image_from_visibility(self.vis, npixel=512, cellsize=0.001,
                                               polarisation_frame=PolarisationFrame('stokesI'))
     self.dirty, sumwt = invert_2d(self.vis, self.model)
     self.psf, sumwt = invert_2d(self.vis, self.model, dopsf=True)
     window = numpy.zeros(shape=self.model.shape, dtype=numpy.bool)
     window[..., 129:384, 129:384] = True
     self.innerquarter = create_image_from_array(window, self.model.wcs)
    def setUp(self):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 300.0, 30.0)
        self.frequency = numpy.linspace(1.0e8, 1.1e8, 3)
        self.channel_bandwidth = numpy.array([1e7, 1e7, 1e7])
        # Define the component and give it some spectral behaviour
        f = numpy.array([100.0, 20.0, -10.0, 1.0])
        self.flux = numpy.array([f, 0.8 * f, 0.6 * f])

        # The phase centre is absolute and the component is specified relative (for now).
        # This means that the component should end up at the position phasecentre+compredirection
        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox=2000.0)
        self.compabsdirection = SkyCoord(ra=+181.0 * u.deg,
                                         dec=-35.0 * u.deg,
                                         frame='icrs',
                                         equinox=2000.0)
        #        self.compabsdirection = SkyCoord(ra=+182 * u.deg, dec=-36.5 * u.deg, frame='icrs', equinox=2000.0)
        pcof = self.phasecentre.skyoffset_frame()
        self.compreldirection = self.compabsdirection.transform_to(pcof)
        self.comp = Skycomponent(direction=self.compreldirection,
                                 frequency=self.frequency,
                                 flux=self.flux)
Example #3
0
 def ingest_visibility(self, freq=None, chan_width=None, times=None, reffrequency=None, add_errors=False,
                       block=True):
     if freq is None:
         freq = [1e8]
     if times is None:
         ntimes = 5
         times = numpy.linspace(-numpy.pi / 3.0, numpy.pi / 3.0, ntimes)
     if chan_width is None:
         chan_width = [1e6]
     
     if reffrequency is None:
         reffrequency = [1e8]
     lowcore = create_named_configuration('LOWBD2-CORE')
     frequency = numpy.array([freq])
     channel_bandwidth = numpy.array([chan_width])
     
     phasecentre = SkyCoord(ra=+180.0 * u.deg, dec=-60.0 * u.deg, frame='icrs', equinox='J2000')
     if block:
         vt = create_blockvisibility(lowcore, times, frequency, channel_bandwidth=channel_bandwidth,
                                     weight=1.0, phasecentre=phasecentre,
                                     polarisation_frame=PolarisationFrame("stokesI"))
     else:
         vt = create_visibility(lowcore, times, frequency, channel_bandwidth=channel_bandwidth,
                                weight=1.0, phasecentre=phasecentre,
                                polarisation_frame=PolarisationFrame("stokesI"))
     cellsize = 0.001
     model = create_image_from_visibility(vt, npixel=self.npixel, cellsize=cellsize, npol=1,
                                          frequency=reffrequency, phasecentre=phasecentre,
                                          polarisation_frame=PolarisationFrame("stokesI"))
     flux = numpy.array([[100.0]])
     facets = 4
     
     rpix = model.wcs.wcs.crpix - 1.0
     spacing_pixels = self.npixel // facets
     centers = [-1.5, -0.5, 0.5, 1.5]
     comps = list()
     for iy in centers:
         for ix in centers:
             p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[0]))), \
                 int(round(rpix[1] + iy * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[1])))
             sc = pixel_to_skycoord(p[0], p[1], model.wcs, origin=1)
             comp = create_skycomponent(flux=flux, frequency=frequency, direction=sc,
                                        polarisation_frame=PolarisationFrame("stokesI"))
             comps.append(comp)
     if block:
         predict_skycomponent_blockvisibility(vt, comps)
     else:
         predict_skycomponent_visibility(vt, comps)
     insert_skycomponent(model, comps)
     self.model = copy_image(model)
     self.empty_model = create_empty_image_like(model)
     export_image_to_fits(model, '%s/test_pipeline_bags_model.fits' % self.dir)
     
     if add_errors:
         # These will be the same for all calls
         numpy.random.seed(180555)
         gt = create_gaintable_from_blockvisibility(vt)
         gt = simulate_gaintable(gt, phase_error=1.0, amplitude_error=0.0)
         vt = apply_gaintable(vt, gt)
     return vt
Example #4
0
    def setUp(self):
        self.dir = './test_results'
        os.makedirs(self.dir, exist_ok=True)

        self.vnchan = 5
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 7)
        self.frequency = numpy.linspace(8e7, 1.2e8, self.vnchan)
        self.startfrequency = numpy.array([8e7])
        self.channel_bandwidth = numpy.array(
            self.vnchan * [self.frequency[1] - self.frequency[0]])
        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.vis = create_visibility(
            self.lowcore,
            times=self.times,
            frequency=self.frequency,
            phasecentre=self.phasecentre,
            weight=1.0,
            polarisation_frame=PolarisationFrame('stokesI'),
            channel_bandwidth=self.channel_bandwidth)
        self.model = create_image_from_visibility(
            self.vis,
            npixel=512,
            cellsize=0.001,
            nchan=self.vnchan,
            frequency=self.startfrequency)
 def createVis(self, config, dec=-35.0):
     self.config = create_named_configuration(config)
     self.phasecentre = SkyCoord(ra=+15 * u.deg, dec=dec * u.deg, frame='icrs', equinox=2000.0)
     self.vis = create_visibility(self.config, self.times, self.frequency,
                                  channel_bandwidth=self.channel_bandwidth,
                                  phasecentre=self.phasecentre, weight=1.0,
                                  polarisation_frame=PolarisationFrame('stokesI'))
Example #6
0
    def setUp(self):
        self.dir = './test_results'
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        os.makedirs(self.dir, exist_ok=True)
        self.times = (numpy.pi / (12.0)) * numpy.linspace(-3.0, 3.0, 7)
        self.frequency = numpy.array([1e8])
        self.channel_bandwidth = numpy.array([1e6])
        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.vis = create_visibility(
            self.lowcore,
            self.times,
            self.frequency,
            channel_bandwidth=self.channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1.0,
            polarisation_frame=PolarisationFrame('stokesI'))
        self.vis.data['vis'] *= 0.0

        # Create model
        self.model = create_test_image(cellsize=0.0015,
                                       phasecentre=self.vis.phasecentre,
                                       frequency=self.frequency)
        self.model.data[self.model.data > 1.0] = 1.0
        self.vis = predict_2d(self.vis, self.model)
        assert numpy.max(numpy.abs(self.vis.vis)) > 0.0
        export_image_to_fits(
            self.model, '%s/test_solve_skycomponent_model.fits' % (self.dir))
        self.bigmodel = create_image_from_visibility(self.vis,
                                                     cellsize=0.0015,
                                                     npixel=512)
Example #7
0
 def setUp(self):
     self.dir = './test_results'
     os.makedirs(self.dir, exist_ok=True)
     self.niter = 1000
     self.lowcore = create_named_configuration('LOWBD2-CORE')
     self.nchan = 5
     self.times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 7)
     self.frequency = numpy.linspace(0.9e8, 1.1e8, self.nchan)
     self.channel_bandwidth = numpy.array(self.nchan * [self.frequency[1] - self.frequency[0]])
     self.phasecentre = SkyCoord(ra=+0.0 * u.deg, dec=-45.0 * u.deg, frame='icrs', equinox='J2000')
     self.vis = create_visibility(self.lowcore, self.times, self.frequency, self.channel_bandwidth,
                                  phasecentre=self.phasecentre, weight=1.0,
                                  polarisation_frame=PolarisationFrame('stokesI'))
     self.vis.data['vis'] *= 0.0
     
     # Create model
     self.test_model = create_low_test_image_from_gleam(npixel=512, cellsize=0.001,
                                                        phasecentre=self.vis.phasecentre,
                                                        frequency=self.frequency,
                                                        channel_bandwidth=self.channel_bandwidth)
     beam = create_low_test_beam(self.test_model)
     export_image_to_fits(beam, "%s/test_deconvolve_msmfsclean_beam.fits" % self.dir)
     self.test_model.data *= beam.data
     export_image_to_fits(self.test_model, "%s/test_deconvolve_msmfsclean_model.fits" % self.dir)
     self.vis = predict_2d(self.vis, self.test_model)
     assert numpy.max(numpy.abs(self.vis.vis)) > 0.0
     self.model = create_image_from_visibility(self.vis, npixel=512, cellsize=0.001,
                                               polarisation_frame=PolarisationFrame('stokesI'))
     self.dirty, sumwt = invert_2d(self.vis, self.model)
     self.psf, sumwt = invert_2d(self.vis, self.model, dopsf=True)
     export_image_to_fits(self.dirty, "%s/test_deconvolve_msmfsclean_dirty.fits" % self.dir)
     export_image_to_fits(self.psf, "%s/test_deconvolve_msmfsclean_psf.fits" % self.dir)
     window = numpy.ones(shape=self.model.shape, dtype=numpy.bool)
     window[..., 129:384, 129:384] = True
     self.innerquarter = create_image_from_array(window, self.model.wcs)
 def setUp(self):
     self.lowcore = create_named_configuration('LOWBD2-CORE')
     self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 60.0, 30.0)
     vnchan = 3
     self.frequency = numpy.linspace(1.0e8, 1.1e8, vnchan)
     self.channel_bandwidth = numpy.array(
         vnchan * [self.frequency[1] - self.frequency[0]])
Example #9
0
    def actualSetUp(self,
                    time=None,
                    frequency=None,
                    dospectral=False,
                    dopol=False):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 5)

        if time is not None:
            self.times = time
        log.info("Times are %s" % (self.times))

        if dospectral:
            self.nchan = 3
            self.frequency = numpy.array([0.9e8, 1e8, 1.1e8])
            self.channel_bandwidth = numpy.array([1e7, 1e7, 1e7])
        else:
            self.frequency = numpy.array([1e8])
            self.channel_bandwidth = numpy.array([1e7])

        if dopol:
            self.vis_pol = PolarisationFrame('linear')
            self.image_pol = PolarisationFrame('stokesIQUV')
        else:
            self.vis_pol = PolarisationFrame('stokesI')
            self.image_pol = PolarisationFrame('stokesI')

        if dopol:
            f = numpy.array([100.0, 20.0, -10.0, 1.0])
        else:
            f = numpy.array([100.0])

        if dospectral:
            numpy.array([f, 0.8 * f, 0.6 * f])
        else:
            numpy.array([f])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.componentvis = create_visibility(
            self.lowcore,
            self.times,
            self.frequency,
            channel_bandwidth=self.channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1.0,
            polarisation_frame=self.vis_pol)
        self.uvw = self.componentvis.data['uvw']
        self.componentvis.data['vis'] *= 0.0

        # Create model
        self.model = create_image_from_visibility(
            self.componentvis,
            npixel=512,
            cellsize=0.001,
            nchan=len(self.frequency),
            polarisation_frame=self.image_pol)
Example #10
0
    def ingest_visibility(self,
                          freq=1e8,
                          chan_width=1e6,
                          times=None,
                          reffrequency=None,
                          add_errors=False):
        if times is None:
            times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 5)

        if reffrequency is None:
            reffrequency = [1e8]
        lowcore = create_named_configuration('LOWBD2-CORE')
        frequency = numpy.array([freq])
        channel_bandwidth = numpy.array([chan_width])

        phasecentre = SkyCoord(ra=+180.0 * u.deg,
                               dec=-60.0 * u.deg,
                               frame='icrs',
                               equinox='J2000')
        vt = create_visibility(lowcore,
                               times,
                               frequency,
                               channel_bandwidth=channel_bandwidth,
                               weight=1.0,
                               phasecentre=phasecentre,
                               polarisation_frame=PolarisationFrame("stokesI"))
        cellsize = 0.001
        model = create_image_from_visibility(
            vt,
            npixel=self.npixel,
            cellsize=cellsize,
            npol=1,
            frequency=reffrequency,
            phasecentre=phasecentre,
            polarisation_frame=PolarisationFrame("stokesI"))
        flux = numpy.array([[100.0]])
        facets = 4

        rpix = model.wcs.wcs.crpix
        spacing_pixels = self.npixel // facets
        centers = [-1.5, -0.5, 0.5, 1.5]
        comps = list()
        for iy in centers:
            for ix in centers:
                p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[0]))), \
                    int(round(rpix[1] + iy * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[1])))
                sc = pixel_to_skycoord(p[0], p[1], model.wcs, origin=0)
                comp = create_skycomponent(
                    flux=flux,
                    frequency=frequency,
                    direction=sc,
                    polarisation_frame=PolarisationFrame("stokesI"))
                comps.append(comp)
        predict_skycomponent_visibility(vt, comps)
        insert_skycomponent(model, comps)
        self.model = copy_image(model)
        export_image_to_fits(model,
                             '%s/test_bags_model.fits' % (self.results_dir))
        return vt
Example #11
0
    def setUp(self):
        self.dir = './test_results'
        os.makedirs(self.dir, exist_ok=True)
        lowcore = create_named_configuration('LOWBD2-CORE')
        times = numpy.arange(-3.0, +3.0, 1.0) * numpy.pi / 12.0
        vnchan = 8
        frequency = numpy.linspace(0.8e8, 1.20e8, vnchan)
        channel_bandwidth = numpy.array(vnchan * [frequency[1] - frequency[0]])

        # Define the component and give it some polarisation and spectral behaviour
        f = numpy.array([100.0, 20.0, -10.0, 1.0])
        self.flux = numpy.array(
            [f, 0.9 * f, 0.8 * f, 0.7 * f, 0.6 * f, 0.5 * f, 0.4 * f, 0.3 * f])

        self.phasecentre = SkyCoord(ra=+15.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.compabsdirection = SkyCoord(ra=17.0 * u.deg,
                                         dec=-36.5 * u.deg,
                                         frame='icrs',
                                         equinox='J2000')

        self.comp = create_skycomponent(flux=self.flux,
                                        frequency=frequency,
                                        direction=self.compabsdirection)
        self.image = create_test_image(
            frequency=frequency,
            phasecentre=self.phasecentre,
            cellsize=0.001,
            polarisation_frame=PolarisationFrame('stokesIQUV'))

        self.blockvis = create_blockvisibility_iterator(
            lowcore,
            times=times,
            frequency=frequency,
            channel_bandwidth=channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1,
            polarisation_frame=PolarisationFrame('linear'),
            integration_time=1.0,
            number_integrations=1,
            predict=predict_2d,
            components=self.comp,
            phase_error=0.1,
            amplitude_error=0.01,
            sleep=1.0)

        self.vis = create_blockvisibility(
            lowcore,
            times=times,
            frequency=frequency,
            channel_bandwidth=channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1,
            polarisation_frame=PolarisationFrame('stokesIQUV'),
            integration_time=1.0)

        self.vis = predict_2d(self.vis, self.image)
 def setUp(self):
     
     self.lowcore = create_named_configuration('LOWBD2-CORE')
     
     self.times = numpy.linspace(-300.0, 300.0, 11) * numpy.pi / 43200.0
     
     self.frequency = numpy.array([1e8])
     self.channel_bandwidth = numpy.array([1e8])
     self.phasecentre = SkyCoord(ra=+15.0 * u.deg, dec=-35.0 * u.deg, frame='icrs', equinox='J2000')
Example #13
0
    def setUp(self):

        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 30 * 3.76, 3.76)
        df = 27343.75000
        self.frequency = numpy.array([1e8 - df, 1e8, 1e8 + df])
        self.channel_bandwidth = numpy.array([27343.75, 27343.75, 27343.75])
        self.phasecentre = SkyCoord(ra=+0.0 * u.deg, dec=-35.0 * u.deg, frame='icrs', equinox='J2000')
        self.blockvis = create_blockvisibility(self.lowcore, self.times, self.frequency, phasecentre=self.phasecentre,
                                               weight=1.0, polarisation_frame=PolarisationFrame('stokesI'),
                                               channel_bandwidth=self.channel_bandwidth)
Example #14
0
def telescope_management_kernel(ixs, config, rmax):
    '''
        生成总的conf类,留待telescope_data_kernel进一步划分
    :param ixs:
    :return: iter[(key, conf)]
    '''
    ix = next(ixs)[0]
    conf = create_named_configuration(config, rmax=rmax)
    result = (ix, conf)
    label = "Telescope Management (0.0 MB, 0.00 Tflop) "
    print(label + str(result))
    return iter([result])
 def setUp(self):
     self.dir = './test_results'
     os.makedirs(self.dir, exist_ok=True)
     
     self.frequency = numpy.linspace(1e8, 1.5e8, 3)
     self.channel_bandwidth = numpy.array([2.5e7, 2.5e7, 2.5e7])
     self.flux = numpy.array([[100.0], [100.0], [100.0]])
     self.phasecentre = SkyCoord(ra=+15.0 * u.deg, dec=-35.0 * u.deg, frame='icrs', equinox=2000.0)
     self.config = create_named_configuration('LOWBD2-CORE')
     self.times = numpy.linspace(-300.0, 300.0, 3) * numpy.pi / 43200.0
     nants = self.config.xyz.shape[0]
     assert nants > 1
     assert len(self.config.names) == nants
     assert len(self.config.mount) == nants
 def test_predict_sky_components_coalesce(self):
     sc = create_low_test_skycomponents_from_gleam(flux_limit=10.0,
                                                   polarisation_frame=PolarisationFrame("stokesI"),
                                                   frequency=self.frequency, kind='cubic',
                                                   phasecentre=SkyCoord("17h20m31s", "-00d58m45s"),
                                                   radius=0.1)
     self.config = create_named_configuration('LOWBD2-CORE')
     self.phasecentre = SkyCoord("17h20m31s", "-00d58m45s")
     sampling_time = 3.76
     self.times = numpy.arange(0.0, + 300 * sampling_time, sampling_time)
     self.vis = create_blockvisibility(self.config, self.times, self.frequency, phasecentre=self.phasecentre,
                                       weight=1.0, polarisation_frame=PolarisationFrame('stokesI'),
                                       channel_bandwidth=self.channel_bandwidth)
     self.vis = predict_skycomponent_blockvisibility(self.vis, sc)
     cvt = coalesce_visibility(self.vis, time_coal=1.0)
     assert cvt.cindex is not None
    def actualSetup(self,
                    sky_pol_frame='stokesIQUV',
                    data_pol_frame='linear',
                    f=None,
                    vnchan=3):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 43200.0) * numpy.linspace(0.0, 30.0, 3)
        self.frequency = numpy.linspace(1.0e8, 1.1e8, vnchan)
        self.channel_bandwidth = numpy.array(
            vnchan * [self.frequency[1] - self.frequency[0]])

        if f is None:
            f = [100.0, 50.0, -10.0, 40.0]

        if sky_pol_frame == 'stokesI':
            f = [100.0]

        self.flux = numpy.outer(
            numpy.array(
                [numpy.power(freq / 1e8, -0.7) for freq in self.frequency]), f)

        # The phase centre is absolute and the component is specified relative (for now).
        # This means that the component should end up at the position phasecentre+compredirection
        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.compabsdirection = SkyCoord(ra=+181.0 * u.deg,
                                         dec=-35.0 * u.deg,
                                         frame='icrs',
                                         equinox='J2000')
        self.comp = Skycomponent(
            direction=self.compabsdirection,
            frequency=self.frequency,
            flux=self.flux,
            polarisation_frame=PolarisationFrame(sky_pol_frame))
        self.vis = create_blockvisibility(
            self.lowcore,
            self.times,
            self.frequency,
            phasecentre=self.phasecentre,
            channel_bandwidth=self.channel_bandwidth,
            weight=1.0,
            polarisation_frame=PolarisationFrame(data_pol_frame))
        self.vis = predict_skycomponent_visibility(self.vis, self.comp)
Example #18
0
 def ingest_visibility(self, freq=1e8, chan_width=1e6, times=None, reffrequency=None, add_errors=False):
     if times is None:
         times = [0.0]
     if reffrequency is None:
         reffrequency = [1e8]
     lowcore = create_named_configuration('LOWBD2-CORE')
     frequency = numpy.array([freq])
     channel_bandwidth = numpy.array([chan_width])
     
     #        phasecentre = SkyCoord(ra=+180.0 * u.deg, dec=-60.0 * u.deg, frame='icrs', equinox='J2000')
     # Observe at zenith to ensure that timeslicing works well. We test that elsewhere.
     phasecentre = SkyCoord(ra=+180.0 * u.deg, dec=-60.0 * u.deg, frame='icrs', equinox='J2000')
     vt = create_blockvisibility(lowcore, times, frequency, channel_bandwidth=channel_bandwidth,
                                 weight=1.0, phasecentre=phasecentre,
                                 polarisation_frame=PolarisationFrame("stokesI"))
     cellsize = 0.001
     model = create_image_from_visibility(vt, npixel=self.npixel, cellsize=cellsize, npol=1,
                                          frequency=reffrequency,
                                          polarisation_frame=PolarisationFrame("stokesI"))
     flux = numpy.array([[100.0]])
     facets = 4
     
     rpix = model.wcs.wcs.crpix - 1.0
     spacing_pixels = self.npixel // facets
     centers = [-1.5, -0.5, 0.5, 1.5]
     comps = list()
     for iy in centers:
         for ix in centers:
             p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[0]))), \
                 int(round(rpix[1] + iy * spacing_pixels * numpy.sign(model.wcs.wcs.cdelt[1])))
             sc = pixel_to_skycoord(p[0], p[1], model.wcs, origin=1)
             comps.append(create_skycomponent(flux=flux, frequency=vt.frequency, direction=sc,
                                              polarisation_frame=PolarisationFrame("stokesI")))
     predict_skycomponent_blockvisibility(vt, comps)
     insert_skycomponent(model, comps)
     self.actualmodel = copy_image(model)
     export_image_to_fits(model, '%s/test_imaging_model.fits' % (self.results_dir))
     if add_errors:
         # These will be the same for all calls
         numpy.random.seed(180555)
         gt = create_gaintable_from_blockvisibility(vt)
         gt = simulate_gaintable(gt, phase_error=1.0, amplitude_error=0.0)
         vt = apply_gaintable(vt, gt)
     return vt
 def actualSetup(self):
     self.lowcore = create_named_configuration('LOWBD2-CORE')
     self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 300.0, 30.0)
     self.times = [0.0]
     self.frequency = numpy.linspace(1.0e8, 1.1e8, 1)
     self.channel_bandwidth = numpy.array([1e7])
     # Define the component and give it some spectral behaviour
     f = numpy.array([100.0, 20.0, -10.0, 1.0])
     self.flux = numpy.array([f, 0.8 * f, 0.6 * f])
     
     f = numpy.array([100.0])
     self.flux = numpy.array([f])
     
     # The phase centre is absolute and the component is specified relative (for now).
     # This means that the component should end up at the position phasecentre+compredirection
     self.phasecentre = SkyCoord(ra=+180.0 * u.deg, dec=-35.0 * u.deg, frame='icrs', equinox='J2000')
     self.comp_actual_direction = SkyCoord(ra=+180.2 * u.deg, dec=-35.1 * u.deg, frame='icrs', equinox='J2000')
     self.comp_start_direction = SkyCoord(ra=+180.0 * u.deg, dec=-35.0 * u.deg, frame='icrs', equinox='J2000')
     self.comp = Skycomponent(direction=self.comp_actual_direction, frequency=self.frequency, flux=self.flux,
                              polarisation_frame=PolarisationFrame("stokesI"))
Example #20
0
    def setUp(self):
        self.dir = './test_results'
        os.makedirs(self.dir, exist_ok=True)
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = numpy.linspace(-3, +3, 13) * (numpy.pi / 12.0)

        self.frequency = numpy.array([1e8])
        self.channel_bandwidth = numpy.array([1e7])

        # Define the component and give it some polarisation and spectral behaviour
        f = numpy.array([100.0])
        self.flux = numpy.array([f])

        self.phasecentre = SkyCoord(ra=+15.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox=2000.0)
        self.compabsdirection = SkyCoord(ra=17.0 * u.deg,
                                         dec=-36.5 * u.deg,
                                         frame='icrs',
                                         equinox=2000.0)

        self.comp = create_skycomponent(
            flux=self.flux,
            frequency=self.frequency,
            direction=self.compabsdirection,
            polarisation_frame=PolarisationFrame('stokesI'))
        self.image = create_test_image(
            frequency=self.frequency,
            phasecentre=self.phasecentre,
            cellsize=0.001,
            polarisation_frame=PolarisationFrame('stokesI'))
        self.image.data[self.image.data < 0.0] = 0.0

        self.image_graph = delayed(create_test_image)(
            frequency=self.frequency,
            phasecentre=self.phasecentre,
            cellsize=0.001,
            polarisation_frame=PolarisationFrame('stokesI'))
Example #21
0
    def setUp(self):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 300.0, 30.0)
        vnchan = 3
        self.frequency = numpy.linspace(1.0e8, 1.1e8, vnchan)
        self.channel_bandwidth = numpy.array(
            vnchan * [self.frequency[1] - self.frequency[0]])

        # Define the component and give it some spectral behaviour
        f = numpy.array([100.0, 20.0, -10.0, 1.0])
        self.flux = numpy.array([f, 0.8 * f, 0.6 * f])

        # The phase centre is absolute and the component is specified relative (for now).
        # This means that the component should end up at the position phasecentre+compredirection
        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.compabsdirection = SkyCoord(ra=+181.0 * u.deg,
                                         dec=-35.0 * u.deg,
                                         frame='icrs',
                                         equinox='J2000')
Example #22
0
    def actualSetup(self, sky_pol_frame='stokesIQUV', data_pol_frame='linear'):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 43200.0) * numpy.arange(0.0, 300.0, 30.0)
        vnchan = 3
        self.frequency = numpy.linspace(1.0e8, 1.1e8, vnchan)
        self.channel_bandwidth = numpy.array(
            vnchan * [self.frequency[1] - self.frequency[0]])

        # Define the component and give it some spectral behaviour
        f = numpy.array([100.0, 20.0, -10.0, 1.0])
        self.flux = numpy.array([f, 0.8 * f, 0.6 * f])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-35.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.compabsdirection = SkyCoord(ra=+181.0 * u.deg,
                                         dec=-35.0 * u.deg,
                                         frame='icrs',
                                         equinox='J2000')
        if sky_pol_frame == 'stokesI':
            self.flux = self.flux[:, 0][:, numpy.newaxis]

        self.comp = Skycomponent(
            direction=self.compabsdirection,
            frequency=self.frequency,
            flux=self.flux,
            polarisation_frame=PolarisationFrame(sky_pol_frame))
        self.vis = create_blockvisibility(
            self.lowcore,
            self.times,
            self.frequency,
            phasecentre=self.phasecentre,
            channel_bandwidth=self.channel_bandwidth,
            weight=1.0,
            polarisation_frame=PolarisationFrame(data_pol_frame))
        self.vis = predict_skycomponent_visibility(self.vis, self.comp)
    def actualSetUp(self,
                    add_errors=False,
                    freqwin=7,
                    block=False,
                    dospectral=True,
                    dopol=False):
        self.low = create_named_configuration('LOWBD2', rmax=750.0)
        self.freqwin = freqwin
        self.vis_graph_list = list()
        self.ntimes = 5
        self.times = numpy.linspace(-3.0, +3.0, self.ntimes) * numpy.pi / 12.0
        self.frequency = numpy.linspace(0.8e8, 1.2e8, self.freqwin)

        if freqwin > 1:
            self.channelwidth = numpy.array(
                freqwin * [self.frequency[1] - self.frequency[0]])
        else:
            self.channelwidth = numpy.array([1e6])

        if dopol:
            self.vis_pol = PolarisationFrame('linear')
            self.image_pol = PolarisationFrame('stokesIQUV')
            f = numpy.array([100.0, 20.0, -10.0, 1.0])
        else:
            self.vis_pol = PolarisationFrame('stokesI')
            self.image_pol = PolarisationFrame('stokesI')
            f = numpy.array([100.0])

        if dospectral:
            flux = numpy.array(
                [f * numpy.power(freq / 1e8, -0.7) for freq in self.frequency])
        else:
            flux = numpy.array([f])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.vis_graph_list = [
            delayed(ingest_unittest_visibility)(self.low, [self.frequency[i]],
                                                [self.channelwidth[i]],
                                                self.times,
                                                self.vis_pol,
                                                self.phasecentre,
                                                block=block)
            for i, _ in enumerate(self.frequency)
        ]

        self.model_graph = [
            delayed(create_unittest_model,
                    nout=freqwin)(self.vis_graph_list[0],
                                  self.image_pol,
                                  npixel=self.params['npixel'])
            for i, _ in enumerate(self.frequency)
        ]

        self.components_graph = [
            delayed(create_unittest_components)(self.model_graph[i],
                                                flux[i, :][numpy.newaxis, :])
            for i, _ in enumerate(self.frequency)
        ]

        # Apply the LOW primary beam and insert into model
        self.model_graph = [
            delayed(insert_skycomponent,
                    nout=1)(self.model_graph[freqwin],
                            self.components_graph[freqwin])
            for freqwin, _ in enumerate(self.frequency)
        ]

        self.vis_graph_list = [
            delayed(predict_skycomponent_visibility)(
                self.vis_graph_list[freqwin], self.components_graph[freqwin])
            for freqwin, _ in enumerate(self.frequency)
        ]

        # Calculate the model convolved with a Gaussian.
        model = self.model_graph[0].compute()
        self.cmodel = smooth_image(model)
        export_image_to_fits(model,
                             '%s/test_imaging_delayed_model.fits' % self.dir)
        export_image_to_fits(self.cmodel,
                             '%s/test_imaging_delayed_cmodel.fits' % self.dir)

        if add_errors and block:
            self.vis_graph_list = [
                delayed(insert_unittest_errors)(self.vis_graph_list[i])
                for i, _ in enumerate(self.frequency)
            ]
def create_simulate_vis_graph(config='LOWBD2-CORE',
                              phasecentre=SkyCoord(ra=+15.0 * u.deg,
                                                   dec=-60.0 * u.deg,
                                                   frame='icrs',
                                                   equinox='J2000'),
                              frequency=None,
                              channel_bandwidth=None,
                              times=None,
                              polarisation_frame=PolarisationFrame("stokesI"),
                              order='frequency',
                              format='blockvis',
                              rmax=1000.0) -> delayed:
    """ Create a graph to simulate an observation

    The simulation step can generate a single BlockVisibility or a list of BlockVisibility's.
    The parameter keyword determines the way that the list is constructed.
    If order='frequency' then len(frequency) BlockVisibility's with all times are created.
    If order='time' then  len(times) BlockVisibility's with all frequencies are created.
    If order = 'both' then len(times) * len(times) BlockVisibility's are created each with
    a single time and frequency. If order = None then all data are created in one BlockVisibility.

    The output format can be either 'blockvis' (for calibration) or 'vis' (for imaging)

    :param config: Name of configuration: def LOWBDS-CORE
    :param phasecentre: Phase centre def: SkyCoord(ra=+15.0 * u.deg, dec=-60.0 * u.deg, frame='icrs', equinox='J2000')
    :param frequency: def [1e8]
    :param channel_bandwidth: def [1e6]
    :param times: Observing times in radians: def [0.0]
    :param polarisation_frame: def PolarisationFrame("stokesI")
    :param order: 'time' or 'frequency' or 'both' or None: def 'frequency'
    :param format: 'blockvis' or 'vis': def 'blockvis'
    :param kwargs:
    :return: vis_graph_list with different frequencies in different elements
    """
    if format == 'vis':
        create_vis = create_visibility
    else:
        create_vis = create_blockvisibility

    if times is None:
        times = [0.0]
    if channel_bandwidth is None:
        channel_bandwidth = [1e6]
    if frequency is None:
        frequency = [1e8]
    conf = create_named_configuration(config, rmax=rmax)

    if order == 'time':
        log.debug("create_simulate_vis_graph: Simulating distribution in %s" %
                  order)
        vis_graph_list = list()
        for i, time in enumerate(times):
            vis_graph_list.append(
                delayed(create_vis,
                        nout=1)(conf, [times[i]],
                                frequency=frequency,
                                channel_bandwidth=channel_bandwidth,
                                weight=1.0,
                                phasecentre=phasecentre,
                                polarisation_frame=polarisation_frame))

    elif order == 'frequency':
        log.debug("create_simulate_vis_graph: Simulating distribution in %s" %
                  order)
        vis_graph_list = list()
        for j, _ in enumerate(frequency):
            vis_graph_list.append(
                delayed(create_vis,
                        nout=1)(conf,
                                times,
                                frequency=[frequency[j]],
                                channel_bandwidth=[channel_bandwidth[j]],
                                weight=1.0,
                                phasecentre=phasecentre,
                                polarisation_frame=polarisation_frame))

    elif order == 'both':
        log.debug(
            "create_simulate_vis_graph: Simulating distribution in time and frequency"
        )
        vis_graph_list = list()
        for i, _ in enumerate(times):
            for j, _ in enumerate(frequency):
                vis_graph_list.append(
                    delayed(create_vis,
                            nout=1)(conf, [times[i]],
                                    frequency=[frequency[j]],
                                    channel_bandwidth=[channel_bandwidth[j]],
                                    weight=1.0,
                                    phasecentre=phasecentre,
                                    polarisation_frame=polarisation_frame))

    elif order is None:
        log.debug("create_simulate_vis_graph: Simulating into single %s" %
                  format)
        vis_graph_list = list()
        vis_graph_list.append(
            delayed(create_vis, nout=1)(conf,
                                        times,
                                        frequency=frequency,
                                        channel_bandwidth=channel_bandwidth,
                                        weight=1.0,
                                        phasecentre=phasecentre,
                                        polarisation_frame=polarisation_frame))
    else:
        raise NotImplementedError("order $s not known" % order)
    return vis_graph_list
    def actualSetUp(self, time=None, frequency=None):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / (12.0)) * numpy.linspace(-3.0, 3.0, 7)

        if time is not None:
            self.times = time
        log.info("Times are %s" % (self.times))

        if frequency is None:
            self.frequency = numpy.array([1e8])
            self.channel_bandwidth = numpy.array([1e7])
        else:
            self.frequency = frequency
            if len(self.frequency) < 1:
                self.channel_bandwidth = numpy.full_like(
                    self.frequency, self.frequency[1] - self.frequency[0])
            else:
                self.channel_bandwidth = numpy.array([1e6])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox=2000.0)
        self.componentvis = create_visibility(
            self.lowcore,
            self.times,
            self.frequency,
            channel_bandwidth=self.channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1.0,
            polarisation_frame=PolarisationFrame('stokesI'))
        self.uvw = self.componentvis.data['uvw']
        self.componentvis.data['vis'] *= 0.0

        # Create model
        self.model = create_image_from_visibility(
            self.componentvis,
            npixel=256,
            cellsize=0.001,
            nchan=1,
            polarisation_frame=PolarisationFrame('stokesI'))

        # Fill the visibility with exactly computed point sources. These are chosen to lie
        # on grid points.
        spacing_pixels = 32
        log.info('Spacing in pixels = %s' % spacing_pixels)

        centers = [-2.5, -0.5, 0.5, 2.5]

        # Make the list of components
        rpix = self.model.wcs.wcs.crpix - 1
        self.components = []
        for iy in centers:
            for ix in centers:
                if ix >= iy:
                    # The phase center in 0-relative coordinates is n // 2 so we centre the grid of
                    # components on ny // 2, nx // 2. The wcs must be defined consistently.
                    p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(self.model.wcs.wcs.cdelt[0]))), \
                        int(round(rpix[1] + iy * spacing_pixels * numpy.sign(self.model.wcs.wcs.cdelt[1])))
                    sc = pixel_to_skycoord(p[0],
                                           p[1],
                                           self.model.wcs,
                                           origin=0)
                    log.info("Component at (%f, %f) [0-rel] %s" %
                             (p[0], p[1], str(sc)))

                    f = (100.0 + 1.0 * ix + iy * 10.0)
                    # Channel images
                    flux = numpy.array([[f]])
                    comp = create_skycomponent(
                        flux=flux,
                        frequency=[numpy.average(self.frequency)],
                        direction=sc,
                        polarisation_frame=PolarisationFrame('stokesI'))
                    self.components.append(comp)

        # Predict the visibility from the components exactly. We always do this for each spectral channel
        self.componentvis.data['vis'] *= 0.0
        predict_skycomponent_visibility(self.componentvis, self.components)
        insert_skycomponent(self.model, self.components)

        # Calculate the model convolved with a Gaussian.
        norm = 2.0 * numpy.pi
        self.cmodel = copy_image(self.model)
        self.cmodel.data[0, 0, :, :] = norm * convolve(
            self.model.data[0, 0, :, :],
            Gaussian2DKernel(1.0),
            normalize_kernel=False)
        export_image_to_fits(self.model, '%s/test_model.fits' % self.dir)
        export_image_to_fits(self.cmodel, '%s/test_cmodel.fits' % self.dir)
Example #26
0
 def test_unknown_configuration(self):
     with self.assertRaises(ValueError):
         self.config = create_named_configuration("SKA1-OWL")
Example #27
0
 def test_clip_configuration(self):
     for rmax in [
             100.0, 3000.0, 1000.0, 3000.0, 10000.0, 30000.0, 100000.0
     ]:
         self.config = create_named_configuration('LOWBD2', rmax=rmax)
         assert self.config.size() > 0.0
    def actualSetUp(self, time=None, dospectral=False, dopol=False):
        self.lowcore = create_named_configuration('LOWBD2-CORE')
        self.times = (numpy.pi / 12.0) * numpy.linspace(-3.0, 3.0, 5)

        if time is not None:
            self.times = time
        log.info("Times are %s" % self.times)

        if dospectral:
            self.nchan = 3
            self.frequency = numpy.array([0.9e8, 1e8, 1.1e8])
            self.channel_bandwidth = numpy.array([1e7, 1e7, 1e7])
        else:
            self.frequency = numpy.array([1e8])
            self.channel_bandwidth = numpy.array([1e7])

        if dopol:
            self.vis_pol = PolarisationFrame('linear')
            self.image_pol = PolarisationFrame('stokesIQUV')
            f = numpy.array([100.0, 20.0, -10.0, 1.0])
        else:
            self.vis_pol = PolarisationFrame('stokesI')
            self.image_pol = PolarisationFrame('stokesI')
            f = numpy.array([100.0])

        if dospectral:
            flux = numpy.array([f, 0.8 * f, 0.6 * f])
        else:
            flux = numpy.array([f])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.componentvis = create_visibility(
            self.lowcore,
            self.times,
            self.frequency,
            channel_bandwidth=self.channel_bandwidth,
            phasecentre=self.phasecentre,
            weight=1.0,
            polarisation_frame=self.vis_pol)
        self.uvw = self.componentvis.data['uvw']
        self.componentvis.data['vis'][...] = 0.0

        # Create model
        self.model = create_image_from_visibility(
            self.componentvis,
            npixel=self.params['npixel'],
            cellsize=0.0005,
            nchan=len(self.frequency),
            polarisation_frame=self.image_pol)

        # Fill the visibility with exactly computed point sources.
        spacing_pixels = 512 // 8
        log.info('Spacing in pixels = %s' % spacing_pixels)

        centers = [(x, x) for x in numpy.linspace(-1.4, +1.4, 9)]

        for x in numpy.linspace(-1.4, +1.4, 9):
            centers.append((-x, x))

        centers.append((0.5, 1.1))
        centers.append((1e-7, 1e-7))

        # Make the list of components
        rpix = self.model.wcs.wcs.crpix
        self.components = []
        for center in centers:
            ix, iy = center
            # The phase center in 0-relative coordinates is n // 2 so we centre the grid of
            # components on ny // 2, nx // 2. The wcs must be defined consistently.
            p = int(round(rpix[0] + ix * spacing_pixels * numpy.sign(self.model.wcs.wcs.cdelt[0]))), \
                int(round(rpix[1] + iy * spacing_pixels * numpy.sign(self.model.wcs.wcs.cdelt[1])))
            sc = pixel_to_skycoord(p[0], p[1], self.model.wcs, origin=1)
            log.info("Component at (%f, %f) [0-rel] %s" %
                     (p[0], p[1], str(sc)))

            if ix != 0 and iy != 0:
                # Channel images
                comp = create_skycomponent(flux=flux,
                                           frequency=self.frequency,
                                           direction=sc,
                                           polarisation_frame=self.image_pol)
                self.components.append(comp)

        # Predict the visibility from the components exactly
        self.componentvis.data['vis'] *= 0.0
        self.beam = create_low_test_beam(self.model)

        self.components = apply_beam_to_skycomponent(self.components,
                                                     self.beam)
        self.componentvis = predict_skycomponent_visibility(
            self.componentvis, self.components)
        self.model = insert_skycomponent(self.model, self.components)

        # Calculate the model convolved with a Gaussian.
        self.cmodel = smooth_image(self.model)
        export_image_to_fits(self.model,
                             '%s/test_imaging_functions_model.fits' % self.dir)
        export_image_to_fits(
            self.cmodel, '%s/test_imaging_functions_cmodel.fits' % self.dir)
Example #29
0
    def actualSetUp(self,
                    add_errors=False,
                    freqwin=1,
                    block=False,
                    dospectral=True,
                    dopol=False):
        self.low = create_named_configuration('LOWBD2', rmax=750.0)
        self.freqwin = freqwin
        self.vis_graph_list = list()
        self.ntimes = 5
        self.times = numpy.linspace(-3.0, +3.0, self.ntimes) * numpy.pi / 12.0
        self.frequency = numpy.linspace(0.8e8, 1.2e8, self.freqwin)
        if freqwin > 1:
            self.channelwidth = numpy.array(
                freqwin * [self.frequency[1] - self.frequency[0]])
        else:
            self.channelwidth = numpy.array([1e6])

        if dopol:
            self.vis_pol = PolarisationFrame('linear')
            self.image_pol = PolarisationFrame('stokesIQUV')
            f = numpy.array([100.0, 20.0, -10.0, 1.0])
        else:
            self.vis_pol = PolarisationFrame('stokesI')
            self.image_pol = PolarisationFrame('stokesI')
            f = numpy.array([100.0])

        if dospectral:
            flux = numpy.array(
                [f * numpy.power(freq / 1e8, -0.7) for freq in self.frequency])
        else:
            flux = numpy.array([f])

        self.phasecentre = SkyCoord(ra=+180.0 * u.deg,
                                    dec=-60.0 * u.deg,
                                    frame='icrs',
                                    equinox='J2000')
        self.componentvis = ingest_unittest_visibility(self.low,
                                                       self.frequency,
                                                       self.channelwidth,
                                                       self.times,
                                                       self.vis_pol,
                                                       self.phasecentre,
                                                       block=block)

        self.model = create_unittest_model(self.componentvis,
                                           self.image_pol,
                                           npixel=self.params['npixel'])

        self.components = create_unittest_components(self.model, flux)
        self.model = insert_skycomponent(self.model, self.components)
        self.componentvis.data['vis'][...] = 0.0
        self.componentvis = predict_skycomponent_visibility(
            self.componentvis, self.components)

        self.cmodel = smooth_image(self.model)
        export_image_to_fits(self.model,
                             '%s/test_imaging_functions_model.fits' % self.dir)
        export_image_to_fits(
            self.cmodel, '%s/test_imaging_functions_cmodel.fits' % self.dir)

        if add_errors:
            self.componentvis = insert_unittest_errors(self.componentvis)
    def test_peel_skycomponent_blockvisibility(self):
        df = 1e6
        frequency = numpy.array([1e8 - df, 1e8, 1e8 + df])
        channel_bandwidth = numpy.array([df, df, df])

        # Define the component and give it some spectral behaviour
        f = numpy.array([100.0, 20.0, -10.0, 1.0])
        flux = numpy.array([f, 0.8 * f, 0.6 * f])
        phasecentre = SkyCoord(0 * u.deg, -60.0 * u.deg)

        config = create_named_configuration('LOWBD2-CORE')
        peeldirection = SkyCoord(+15 * u.deg, -60.0 * u.deg)
        times = numpy.linspace(-3.0, 3.0, 7) * numpy.pi / 12.0

        # Make the visibility
        vis = create_blockvisibility(
            config,
            times,
            frequency,
            phasecentre=phasecentre,
            weight=1.0,
            polarisation_frame=PolarisationFrame('linear'),
            channel_bandwidth=channel_bandwidth)
        vis.data['vis'][...] = 0.0

        # First add in the source to be peeled.
        peel = Skycomponent(direction=peeldirection,
                            frequency=frequency,
                            flux=flux,
                            polarisation_frame=PolarisationFrame("stokesIQUV"))
        vis = predict_skycomponent_visibility(vis, peel)

        # Make a gaintable and apply it to the visibility of the peeling source
        gt = create_gaintable_from_blockvisibility(vis, timeslice='auto')
        gt = simulate_gaintable(gt,
                                phase_error=0.01,
                                amplitude_error=0.01,
                                timeslice='auto')
        gt.data['gain'] *= 0.3
        vis = apply_gaintable(vis, gt, timeslice='auto')

        # Now create a plausible field using the GLEAM sources
        model = create_image_from_visibility(
            vis,
            cellsize=0.001,
            frequency=frequency,
            polarisation_frame=PolarisationFrame('stokesIQUV'))

        bm = create_low_test_beam(model=model)
        sc = create_low_test_skycomponents_from_gleam(
            flux_limit=1.0,
            polarisation_frame=PolarisationFrame("stokesIQUV"),
            frequency=frequency,
            kind='cubic',
            phasecentre=phasecentre,
            radius=0.1)
        sc = apply_beam_to_skycomponent(sc, bm)
        # Add in the visibility due to these sources
        vis = predict_skycomponent_visibility(vis, sc)
        assert numpy.max(numpy.abs(vis.vis)) > 0.0

        # Now we can peel
        vis, peel_gts = peel_skycomponent_blockvisibility(vis, peel)

        assert len(peel_gts) == 1
        residual = numpy.max(peel_gts[0].residual)
        assert residual < 0.7, "Peak residual %.6f too large" % (residual)

        im, sumwt = invert_timeslice(vis, model, timeslice='auto')
        qa = qa_image(im)

        assert numpy.abs(qa.data['max'] - 14.2) < 1.0, str(qa)