Utilities

Your might find these functions useful.

Functions

scatterbrane.utilities.FTElementFast(img, dx, baseline)

Return complex visibility.

Parameters:
  • img – (n, n) numpy image array
  • dx – scalar Pixel size in microarcseconds
  • baseline – (2, ) (u,v) point in wavelengths

Note

To shift center try multipliny by \(\mathrm{exp}(\pi i u n_x\Delta_x)\) and watch out for the axis orientation.

scatterbrane.utilities.ensembleSmooth(img, dx, brane, return_kernel=False)

Generates ensemble averaged image given scattering kernel parameters.

Parameters:
  • img – (n, n) numpy array
  • dx – scalar Pixel scale in microarcseconds
  • brane – Brane object.
  • return_kernel – (optional) bool Return tuple with uv kernel (nump.fft.rfft2() format). See getUVKernel() for an alternate method.
scatterbrane.utilities.getUVKernel(u, v, brane)

Get ensemble kernel in visibility plane for specified uv points. See func:ensembleSmooth for an althernate method.

Parameters:
  • u – (n, ) Samples of u in units of wavelengths.
  • v – (n, ) Samples of v in units of wavelengths.
  • brane – Brane object
Returns:

(n, ) Ensemble kernel complex visibility
scatterbrane.utilities.loadSettings(filename)
Loads simulation settings from a file generated by Brane.save_settings().
Parameters:filename – string File name that contains simulation settings.
Returns:A dictionary with simulation settings.
scatterbrane.utilities.regrid(a, inx, idx, onx, odx)

Regrids array with a new resolution and pixel number.

Parameters:
  • a – (n, n) Input numpy image
  • inx – int Number of input pixels on a side
  • idx – scalar Input resolution element
  • onx – int Number of output pixels on a side
  • odx – scalar Output resolution element
Returns:

Array regridded to the new resolution and field of view.
scatterbrane.utilities.smoothImage(img, dx, fwhm)

Returns Image smoothed by a gaussian kernel.

Parameters:
  • img – (n, n) numpy array
  • dx – scalar Pixel scale in microarcseconds
  • fwhm – scalar Gaussian full width at half maximum in microarcseconds
scatterbrane.utilities.writefits(m, dx, dest='image.fits', obsra=266.4168370833333, obsdec=-29.00781055555555, freq=230000000000.0)

Write fits file with header. Defaults are set for Sgr A* at 1.3mm.

Parameters:
  • m – (n, n) numpy image array
  • dx – scalar Pixel size in microarcseconds
  • dest – (optional) string Output fits file name
  • obsra – (optional) scalar Source right ascension
  • obsdec – (optional) scalar Source declination