\begin{table}%t1 \caption{\label{tab1}Log of observations of Pollux (for details, see Sects. 2 and 3).} %\centerline { \begin{tabular}{c c c c c c c c c c} \hline\hline Date &Instrument& Stokes V & {\it S/N} & HJD &Phase & $B_{\rm l}$ & $\sigma$ & $S$-index &RV \\ & & & &(2~450~000+)& & G & G & Ca~{\sc ii} & km s$^{-1}$ \\ \hline 29 Sep.--02 Oct. 07 & ESPaDOnS &4 & 1196 & 4375.1 & 0.25 &--0.67 & 0.26 & 0.1090 & 3.651 \\ 12 Dec.--18 Dec. 07 & NARVAL &6 & 1792 & 4450.7 & 0.38 &--0.51 & 0.14 & 0.1234 & (3.557) \\ 31 Dec. 07 & ESPaDOnS &5 & 1327 & 4467.0 & 0.40 &--0.57 & 0.19 & 0.1081 & 3.538 \\ 05 Apr. 08 & NARVAL &4 & 1986 & 4562.4 & 0.57 &--0.15 & 0.15 & 0.1263 & 3.532 \\ 15 Apr. 08 & NARVAL &8 & 960 & 4572.4 & 0.58 &--0.12 & 0.23 & 0.1267 & 3.508 \\ 16 Sep. 08 & NARVAL &8 & 1566 & 4726.7 & 0.85 &--0.45 & 0.13 & 0.1249 & 3.551 \\ 20 Sep.--21 Sep. 08 & NARVAL &8 & 1328 & 4731.2 & 0.86 &--0.21 & 0.16 & 0.1262 & 3.576 \\ 30 Sep. 08 & NARVAL &8 & 1955 & 4740.7 & 0.87 &--0.27 & 0.11 & 0.1240 & 3.584 \\ 21 Dec. 08 & NARVAL &8 & 1532 & 4822.6 & 0.01 &--0.33 & 0.14 & 0.1255 & 3.616 \\ 25 Feb. 09 & NARVAL &8 & 1934 & 4888.3 & 0.12 &--0.59 & 0.11 & 0.1259 & 3.633 \\ 12 Mar. 09 & NARVAL &8 & 1190 & 4903.4 & 0.15 &--0.69 & 0.14 & 0.1239 & 3.640 \\ 18 Mar. 09 & NARVAL &15 & 1528 & 4909.4 & 0.16 &--0.56 & 0.10 & 0.1225 & (3.634) \\ 18 Oct. 08 & ESPaDOnS &1 & 1839 & 4759.1 & 0.90 &--1.40 & 0.35 & 0.1102 & 3.586 \\ \hline \end{tabular}} \medskip Notes: Individual columns report dates of observation, instrument, number of averaged Stokes $V$ series, mean peak {\it S/N} in Stokes $I$ for one spectrum, mean HJD, Phase according to Hatzes et~al. (\cite{Hatzes2006}), $B_{\rm l}$ and its error in G, the $S$-index for Ca~{\sc ii} H and K, and the radial velocity measured from the LSD Stokes $I$ profile. \end{table}