psf.py 文件源码

def GetSigma():
  '''
  Get the standard deviation of the Gaussian PSF. I find `sigma` = 0.45 pixels.
  I also plotted the `x` and `y` obtained below to find that average the maximum extent of
  the stellar motion is x,y ~ y,x ~ (2.5, 3.5).

  '''

  star = Everest(os.path.join(TRAPPIST_OUT, 'nPLDTrappist.fits'), TRAPPIST_EPIC)
  fpix = star.fpix.reshape(-1, 6, 6).swapaxes(1,2)
  guess = [3., 3., 1e4, 1e2, 0.5]
  n = 0
  niter = len(fpix) // 10
  x = np.zeros(niter)
  y = np.zeros(niter)
  a = np.zeros(niter)
  b = np.zeros(niter)
  sigma = np.zeros(niter)
  for n in prange(niter):
    x[n], y[n], a[n], b[n], sigma[n] = fmin(ChiSq, guess, args = (fpix[n * 10],), disp = 0)
  return np.nanmedian(sigma)