def Sensitivity(self):
        """Sensitivity spectrum to convert flux in
        :math:`erg \\; cm^{-2} \\; s^{-1} \\; \\AA^{-1}` to
        :math:`count s^{-1} \\AA^{-1}`. Calculation is done by
        combining the throughput curves with
        :math:`\\frac{h \\; c}{\\lambda}` .

        Returns
        -------
        sensitivity : `~pysynphot.spectrum.TabularSpectralElement`

        """
        sensitivity = spectrum.TabularSpectralElement()

        product = self._multiplyThroughputs()

        sensitivity._wavetable = product.GetWaveSet()
        sensitivity._throughputtable = product(sensitivity._wavetable) * \
                                      sensitivity._wavetable * self._constant

        return sensitivity