code: def sersic_constant(self):
          
          return (2 * self.sersic_index) - (1. / 3.) + (4. / (405. * self.sersic_index)) + (
                  46. / (25515. * self.sersic_index ** 2)) + (131. / (1148175. * self.sersic_index ** 3)) - (
                         2194697. / (30690717750. * self.sersic_index ** 4))
docs: A parameter derived from Sersic index which ensures that effective radius contains 50% of the profile's
          total integrated light.