H-TF29 by CDGM

$$n(\lambda) = \sqrt{1 + \frac{0.311396\,\lambda^2}{\lambda^2 - 0.053507} + \frac{1.70917\,\lambda^2}{\lambda^2 - 0.0119663} + \frac{2.21766\,\lambda^2}{\lambda^2 - 170.99}}$$

$$\frac{dn}{dT} = \frac{n_0^2 - 1}{2\,n_0}\left[-2.75 \times 10^{-7} + 2(1.1 \times 10^{-8})\,\Delta T + 3(-3.29 \times 10^{-11})\,\Delta T^2 + \frac{9.44 \times 10^{-7} + 2(9.65 \times 10^{-10})\,\Delta T}{\lambda - 0.259}\right] \Delta T = T - T_0, \quad T_0 = 20\,°\text{C}$$