Schwarzschild ISCO orbital frequency
= Schwarzschild ISCO orbital frequency
{c}
{title2=$f_{\mathrm{ISCO},\infty}=c^3/(2\pi6^{3/2}GM)$}
The Schwarzschild coordinate rotation <frequency> at the marginally stable circular orbit, measured per unit time of a stationary clock at infinity. It scales inversely with black-hole <mass>. A finite-radius static clock adds a gravitational time-dilation factor; a quasi-periodic brightness signal need not directly equal this orbital <frequency>.