Sergiy Shelyag and Paul Cally

Measurements made around active regions are complicated by magneto-acoustic mode-conversion and changes in the radiative properties of magnetic field concentrations. Forward modelling has been performed using the SPARC numerical code in a semi-empirical magneto-hydrostatic model of a large-scale solar magnetic field mimicking a sunspot. The 6173 A absorption line used by the HMI instrument has been synthesized at various positions on the solar disk. Using the response of this spectrum at different observational inclinations slow modes are seen in the sunspot umbra.