= Chirp mass
{title2=$\mathcal M=(m_1m_2)^{3/5}/(m_1+m_2)^{1/5}$}
{wiki}
The <chirp mass> is the combination of two component <masses> controlling the leading <Newtonian binary chirp>. Inverting its frequency equation gives
$$
\mathcal M=\frac{c^3}{G}\left[\frac{5}{96}\pi^{-8/3}f^{-11/3}\dot f\right]^{3/5}.
$$
Use $f$ in hertz and $\dot f$ in hertz per second to obtain kilograms. For equal component <masses> $m$, $\mathcal M=m/2^{1/5}$. A stipulated $20+20$ <solar mass> system therefore has $\mathcal M\approx17.411$ <solar masses>. In a cosmological observation the time and frequency measured at the detector instead yield $(1+z)\mathcal M_{\rm source}$, where $z$ is <redshift>; phase evolution alone does not independently determine the source <mass> and <redshift>.
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