What does this equation mean?

where the “range” parameter r is set directly by the companion’s mass and the “shape” parameter s by the orbit’s inclination. Because r and s are measured independently of the pulsar’s own mass, and Kepler’s laws already fix the total system mass from the orbital period and velocity, a sufficiently edge-on, sufficiently precisely timed binary hands over both masses at once — no assumptions about the neutron star’s interior required. The catch is precision: resolving a mass difference of a few hundredths of a solar mass means resolving a timing residual measured in tens of nanoseconds across years of observation, which is why the equipment built for this work is built around atomic-clock frequency standards and years of accumulated data rather than any single observation.