code: def sky_sep(self, pix1, pix2):
          
          pos1 = self.pix2sky(pix1)
          pos2 = self.pix2sky(pix2)
          sep = gcd(pos1[0], pos1[1], pos2[0], pos2[1])
          return sep
docs: calculate the GCD sky separation (degrees) between two pixels.
  
          Parameters
          ----------
          pix1, pix2 : (float, float)
              The (x,y) pixel coordinates for the two positions.
  
          Returns
          -------
          dist : float
              The distance between the two points (degrees).