Converting CaII to \(\log R'_\text{HK}\)

Use pyrhk to convert the I_CaII index from ACTIN to the \(S_\mathrm{MW}\) scale using the pyrhk.calc_smw function and then convert the \(S_\mathrm{MW}\) values to \(\log R'_\mathrm{HK}\) using pyrhk.calc_rhk. Various calibrations are available for different instruments and stellar types.