\begin{table}%t1 %\centering \par \caption{\label{already_known_CP_IPs}Summary of previously measured circular polarization in IPs.} \small \begin{tabular}{llllllll} \hline\hline Name & Wavelength range$^a$ & Mean & Min & Max & Integration time & Total time & Ref.$^1$\\ & (nm) & (\%) & (\%) & (\%) & (s) & &\\ \hline AE Aqr & 350--920 & $-0.03\pm0.02$ & & & 15 & 140~min& 1\\ & {\it I} & $-0.06\pm0.03$ & & & 15 & 150~min & 1\\ & 350--570 & $-0.06\pm0.02$ & & & 5 & 390~min& 1\\ & 320--860 & $+0.01\pm0.02$ & & & 8$\times I^c$ & $\times$2 & 2\\ & 590--860 & $-0.01\pm0.01$ & & & 1$^d$ & 34~min & 2\\ & 320--860 & $-0.13\pm0.03$ & & & $8\times I^c$ & $\times$5 & 2\\ & 320--860& $+0.01\pm0.01$ & & & $8~\times~~I^c$ & $\times$3 & 2\\ & 1150--1350 & $+0.06\pm0.08$ & & & & 4~min & 2\\ & 1450--1650 & $-0.80\pm0.60$ & & & & 7~min & 2\\ & 500--750 & $+0.07\pm0.02$ & & & 5 & 255~min & 3\\ %\cite{beskrovnaya96}\\ & (550) & $+0.06\pm0.01$ & & & 5 & 323~min & 3\\ %\cite{beskrovnaya96}\\ AO Psc & 570--920 & $+0.03\pm0.03$ & & & 240 & 180~min & 1\\ %\cite{cropper86}\\ & $I$ & & & & 240 & 180~min & 1\\ %\cite{cropper86}\\ & 320--860 & $-0.05\pm0.06$ & & & $8\times I^c$ & $\times$1 & 2\\ & 660--860 & $+0.00\pm0.07$ & & & $8\times I^c$ & $\times$3 & 2\\ & 320--860 & $+0.03\pm0.03$ & & & $8\times I^c$ & $\times$2 & 2\\ BG CMi & 640--860 & $-0.24\pm0.03$ & & & $2~\times~~ \sim 30$ & & 4\\ %\cite{penning86}\\ & 320--860 & $-0.05\pm0.05$ & & & & & 5\\ %\cite{west87}\\ & 720--860 & $-0.25\pm0.06$ & & & & & 5\\ %\cite{west87}\\ & 1110--1380(1250) & $-1.74\pm0.26$ & & & & & 5\\ %\cite{west87}\\ & 1400--1650(1500) & $-4.24\pm1.78$ & & & & & 5\\ %\cite{west87}\\ DQ Her & 370--580 & & $-0.6^b$ & $+0.6^b$ & 14.2 & $\sim$1980~min & 6\\ %\cite{swedlund74}\\ & 320--860 & $+0.01\pm0.01$ & & & & 250~min & 2\\ %\cite{stockman92}\\ EX Hya & 570--920 & $-0.02\pm0.04$ & & & 240 & 200~min & 1\\ %\cite{cropper86}\\ & 590--860 & $+0.01\pm0.02$ & & & 2$^d$ & 68~min & 2\\ %\cite{stockman92}\\ FO Aqr & 640--860 & $+0.06\pm0.02$ & & & & & 4\\ %\cite{penning86}\\ & 330--920 & $-0.01\pm0.02$ & & & 120 & 200~min & 1\\ %\cite{cropper86}\\ & {\it I} & $+0.11\pm0.07$ & & & 240 & 200~min & 1\\ %\cite{cropper86}\\ & 320--860 & $-0.06\pm0.04$ & & & $8\times I^c$ & $\times$2 & 2\\ %\cite{stockman92}\\ & 320--860 & $+0.01\pm0.04$ & & & $8\times I^c$ & $\times$6 & 2\\ %\cite{stockman92}\\ & 720--860 & $-0.01\pm0.17$ & & & $8\times I^c$ & $\times$5 & 2\\ %\cite{stockman92}\\ & 1150--1350 & $+0.19\pm0.13$ & & & & 51~min & 2\\ %\cite{stockman92}\\ & 1150--1350 & $+1.09\pm0.31$ & & & & 141~min & 2\\ %\cite{stockman92}\\ & Visual & $+0.11\pm0.13$ & $-0.2^b$ & $+0.3^b$ & 28 & 270~min & 7\\ %\cite{berriman86} & IR & $-0.01\pm0.55$ & $-1.3^b$ & $+0.8^b$ & 28 & 270~min & 7\\ %\cite{berriman86} GK Per & 1150--1350 & $+0.03\pm0.10$ & & & & 45~min & 2\\ %\cite{stockman92}\\ PQ Gem & {\it U} & $+0.0\pm0.6$ & & & & 80~min & 8\\ %\cite{rosen93}\\ & {\it B} & $+0.0\pm0.6$ & & & & 80~min & 8\\ %\cite{rosen93}\\ & {\it V} & $+0.0\pm0.9$ & & & & 80~min & 8\\ %\cite{rosen93}\\ & {\it R} & & $-1.1$ & $+0.6$ & & 80~min & 8\\ %\cite{rosen93}\\ & {\it U} & & $-0.4^b$ & $+0.3^b$ & $8\times 5$ & 162~min & 9\\ %\cite{piirola93}\\ & {\it B} & & $-0.3^b$ & $+0.4^b$ & $8\times 5$ & 162~min & 9\\ %\cite{piirola93}\\ & {\it V} & & $-0.7^b$ & $+0.7^b$ & $8\times 5$ & 162~min & 9\\ %\cite{piirola93}\\ & {\it R} & & $-1.5^b$ & $+0.7^b$ & $8\times 5$ & 162~min & 9\\ %\cite{piirola93}\\ & {\it I} & & $-2.7$ & $+1.5$ & $8\times 5$ & 162~min & 9\\ %\cite{piirola93}\\ & {\it U} & & $-0.5^b$ & $+0.3^b$ & & $\sim$730~min & 10\\ %\cite{potter97}\\ & {\it B} & & $-0.2^b$ & $+0.3^b$ & & $\sim$730~min & 10\\ %\cite{potter97}\\ & {\it V} & & $-0.6^b$ & $+0.4^b$ & & $\sim$730~min & 10\\ %\cite{potter97}\\ & {\it R} & & $-1.0^b$ & $+0.2^b$ & & $\sim$730~min & 10\\ %\cite{potter97}\\ & {\it I} & & $-1.3^b$ & $+1.3^b$ & & $\sim$730~min & 10\\ %\cite{potter97}\\ & {\it J} & & $-1.2^b$ & $+1.0^b$ & & $\sim$270~min & 10\\ %\cite{potter97}\\ & {\it K} & & $-2.0^b$ & $+1.3^b$ & & $\sim$460~min & 10\\ %\cite{potter97}\\ RXJ2133 & (360) & $+0.90\pm0.06$ & $-0.2^b$ & $+1.5$ & $4\times24$ & 229~min & 11\\ %\cite{katajainen07}\\ & (440) & $+1.12\pm0.05$ & $+0.2^b$ & $+2.5$ & $4\times24$ & 229~min & 11\\ %\cite{katajainen07}\\ & (530) & $+1.17\pm0.09$ & $-0.3^b$ & $+3.5$ & $4\times24$ & 229~min & 11\\ %\cite{katajainen07}\\ & (690) & $+0.85\pm0.07$ & $+0.2^b$ & $+3$ & $4\times24$ & 229~min & 11\\ %\cite{katajainen07}\\ & (830) & $+0.89\pm0.08$ & $-0.4^b$ & $+2.5$ & $4\times24$ & 229~mn & 11\\ TV Col & 640--860 & $-0.03\pm0.04$ & & & & & 4\\ & 320--860 & $-0.13\pm0.09$ & & & $8\times I^c$ & $\times$1 & 2\\ & 320--860 & $-0.07\pm0.07$ & & & $8\times I^c$ & $\times$3 & 2\\ & 320--860 & $-0.08\pm0.10$ & & &$8\times I^c$ & $\times$1 & 2\\ V1223 Sgr & 350--920 & $-0.06\pm0.03$ & & & 240 & 144~min & 1\\ \hline & {\it I}+ {\it R} & $-0.04\pm0.07$ & & & 240 & 563~min & 1\\ & {\it V} & $-0.48\pm0.62$ & $\gtrsim$$-2$ & $\lesssim$$+2$ & 14 & & 12\\ & {\it R} & $+0.03\pm0.13$ & $\gtrsim-0.5$ & $\lesssim$$+0.5$ & 14 & & 12\\ & {\it J} & $-0.36\pm0.13$ & $\gtrsim-1$ & $\lesssim+$$0.5$ & 14 & & 12\\ & {\it K} & $+1.14\pm1.26$ & $\gtrsim$$-8$ & $\lesssim$$+8$ & 14 & & 12\\ V2306 Cyg & (360) & $+0.04\pm0.06$ & & & $8 \times 10$ (210) & 872~min & 13\\ & (440) & $+0.16\pm0.08$ & & & $8 \times 10$ (210) & 872~min & 13\\ & (530) & $+0.18\pm0.11$ & & & $8\times10$ (210) & 872~min & 13\\ & (690) & $-0.55\pm0.08$ & $-1.3^b$ & $+1^b$ & $8 \times 10$ (210) & 872~min & 13\\ & (830) & $-0.91\pm0.14$ & $-1.7^b$ & $+0.4^b$ & $8 \times 10$ (210) & 872~min & 13\\ & {\it B} & $+0.32\pm0.10$ & $-0.3^b$ & $+0.7^b$ & 58 & 52~min & 14\\ & {\it R} & $-1.99\pm0.11$ & $-5.2^b$& $-0.6^b$& 45 & 55~min & 14\\ V2400 Oph & WL & & $-2.9^b$ & $-1.0^b$ & 120 \& 180 & $\sim$900~min & 15\\ & {\it V} & $\sim$$-1.8^b$ & $-4.8^b$ & $-1.0^b$ & 120 & $\sim$33~min & 15\\ & {\it R} & $\sim$$-2.3^b$ & $-5.1^b$ & $-0.5^b$ & 120 & $\sim$71~min & 15\\ & {\it I} & $\sim$$-3.3^b$ & $-6.0^b$ & $-1.0^b$ & 120 & $\sim$32~min & 15\\ & 320--700 (470) & $-0.90\pm0.03$ & & & 50 & & 16\\ & 560--900 (700) & $-2.82\pm0.04$ & & & 50 & & 16\\ V405 Aur & 500--750 & 1.8 (Semi-amp) & & & & & 17\\ & {\it U} & & $-2$ & $+2$ & $8 \times 12$ (96) & 1328~min & 18\\ & {\it B} & & $-3$ & $+3$ & $8 \times 12$ (96) & 1328~min & 18\\ & {\it V} & & $-3$ & $+3$ & $8\times12$ (96) & 1328~min & 18\\ & {\it R} & & $-2$ & $+2$ & $8 \times 12$ (96) & 1328~min & 18\\ & {\it I} & & $-1$ & $+1$ & $8 \times 12$ (96) & 1328~min & 18\\ YY Dra & 320--860 & $+0.09\pm0.10$ & & & $8\times I^c$ & $\times$1 & 2\\ \hline \end{tabular} \medskip $^a$~Numbers in parentheses indicate the effective wavelength of the filter; $^b$~estimated from plots; $^c$~$I$ corresponds to an unspecified time between 0.5--1~mn; $^d$~constant polarimeter position.\\ $^1$ References -- (1) \citet{cropper86}; (2) \citet{stockman92}; (3) \citet{beskrovnaya96}; (4) \citet{penning86}; (5) \citet{west87}; (6)~\citet{swedlund74}; (7)~\citet{berriman86}; (8) \citet{rosen93}; (9)~\citet{piirola93}; (10) \citet{potter97}; (11)~\citet{katajainen07}; (12) \citet{watts85}; (13) \citet{uslenghi01}; (14) \citet{norton02}; (15) \citet{buckley95}; (16) \citet{buckley97}; (17) \citet{shakhovskoj97}; (18) \citet{piirola08}. \end{table}