(unit)             Value     Uncertainty
  ---------------------------- ------------------------- --------- -------------
  Semi-major axis              a (”)                     1.06      $0.02$
  Eccentricity                 e                         0.766     $0.004$
  Inclination                  i ($^\circ$)              39        $2$
  Ascending node               $\Omega$ ($^\circ$)       41        $2$
  Longitude of pericenter      $\omega$ ($^\circ$)       116       $2$
  Date of pericenter passage   T (yr)                    1997.62   $0.05$
  Period                       P (yr)                    56.3      $0.1$
  Total mass                   $M_{\rm tot} (M_\odot)$   1.4       $0.1$

  : 99 Her orbital elements, system mass and 1$\sigma$ uncertainties. The ascending node $\Omega$ is measured anti-clockwise from North. The longitude of pericenter is measured anti-clockwise from the ascending node, and projected onto the sky plane has a position angle of 163$^\circ$ (i.e. is slightly different to 41+116 because the orbit is inclined).[]{data-label="tab:elem"}

![99 Her binary orbit as seen on the sky, with the line of nodes and pericenter indicated. North is up and East is left. The stellar orbits are shown over one (anti-clockwise) orbital period with black dots. Grey dots (primary is the larger grey dot) show the positions at the PACS observation epoch. Black dot sizes are scaled in an arbitrary way such that larger dots are closer to Earth. The arrows indicate the direction of motion and the scale bar indicates the binary semi-major axis of 1.06” (16.5AU).[]{data-label="fig:sys"}](systop.eps){width="50.00000%"}

To interpret the 