H-BAF8 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{1.18829\,\lambda^2}{\lambda^2 - 128.447} + \frac{1.43849\,\lambda^2}{\lambda^2 - 0.0101638} + \frac{0.140002\,\lambda^2}{\lambda^2 - 0.0524583}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-1.87 \times 10^{-6} + 2(1.33 \times 10^{-8})\,\Delta T + 3(-5.61 \times 10^{-11})\,\Delta T^2 + \frac{7.52 \times 10^{-7} + 2(7.56 \times 10^{-10})\,\Delta T}{\lambda - 0.253}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$