Magnitude should be a scale

[dieudonneWillems]

The quantity Magnitude is used as a scale (formalised by Norman Robert Pogson). The magnitude of Vega is defined as the zero point. Problem is that the scale is logarithmic and can at the moment not be defined in OM (apart from using fixed points). Is it possible to also be able to define scale calculus for the magnitude scale?

The relation between the flux density and magnitude is:

$$m_x = -2,5 log_{10}(F_x/F_{x,0})$$

where $$F_x$$ is the flux density for a specific filter and $$F_{x,0}$$ is the reference flux density of the filter.

[HajoRijgersberg]

OM 1 used to have definition_descrition for scales, a text field like (for the CelsiusScale): om:definition_descriptiont90/°C = T90/K - 273.15</om:definition_description> The line is still in OM 2, but commented out. The formulation was meant as a first step towards - hopefully - in the future a more formal description. (Further) ideas are welcome.