code: def estimate_pos_and_err_parabolic(tsvals):
      
      a = tsvals[2] - tsvals[0]
      bc = 2. * tsvals[1] - tsvals[0] - tsvals[2]
      s = a / (2 * bc)
      err = np.sqrt(2 / bc)
      return s, err
docs: Solve for the position and uncertainty of source in one dimension
           assuming that you are near the maximum and the errors are parabolic
  
      Parameters
      ----------
      tsvals  :  `~numpy.ndarray`
         The TS values at the maximum TS, and for each pixel on either side
  
      Returns
      -------
      The position and uncertainty of the source, in pixel units
      w.r.t. the center of the maximum pixel