## Fig. 10

Analysis of the empirical uncertainty for short term repeat observations of RV using filter HR10 and HR21. Plots **a) **and **d) **show the variation of *E*_{RV} with *v*sin*i*. Red lines show the curves predicted using the model value of *C* (see Eq. (A.4)). The dashed lines shows the curves predicted using values of *B* and *C* fitted to the binned data. Plots **b) **and **e) **show the variation in the estimated value of parameter *B* in Eq. (1) with S/N. Red lines show values of *B* fitted to the full dataset for each filter. Blue crosses show the estimated values *B* as a function of S/N corrected for the measured variation of *B* with *T*_{eff} (see Table 3). Plots c and f show the normalised uncertainty for short term repeats and long term repeats. The black curve shows the CDF for short-term repeats. The red line shows the CDF for long-term repeats. Blue diamonds show a Student’s t-distribution with *ν* = 6, which matches the distribution for short-term repeats well.