Abstract
We have acquired high-resolution echelle spectra of 225 F6-M5 type stars in the Southern hemisphere. The stars are targets or candidates to be targets for the Anglo-Australian Planet Search. Ca ii H& K line cores were used to derive activity indices for all of these objects. The indices were converted to the Mt. Wilson system of measurements and log R′HK values determined. A number of these stars had no previously derived activity indices. In addition, we have also included the stars from Tinney et al. using our Mt. Wilson calibration. The radial-velocity instability (also known as jitter) level was determined for all 21 planet-host stars in our data set. We find the jitter to be at a level considerably below the radial-velocity signatures in all but one of these systems. 19 stars from our sample were found to be active (logR′HK > −4.5) and thus have high levels of jitter. Radial-velocity analysis for planetary companions to these stars should proceed with caution.
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