Surface gravity versus effective temperature derived by the SAPP (black diamonds with error bars). The K dwarf GJ 105A is not visible since its parameters are outside of the axis ranges. Small dots represent a subset of the grid of stellar evolution models used by the photometric module as described in Sect. 3.1, selected for this illustration to have an age of 13 Gyr, colour-coded by metallicity, with masses increasing from 0.1 M_⊙ at the lower right towards the upper left with steps of 0.005 M_⊙. We note that when constructing the PDF for surface gravity the photometric module uses the whole grid of models for all available ages.