\begin{table}%t1
\caption{\label{Sample_properties}General properties of the sample.}
\small%\centerline
 {
\begin{tabular}{ccccccc}
\hline
\hline \noalign{\smallskip}
Name & Ra (2000) & Dec (2000) & $12+\log({\rm O/H})^{a}$ & Distance (Mpc)$^{b}$ & $M$(HI)$^{c}$ & Apparent size \\
\hline
\noalign{\smallskip}
NGC~1705 & 04h54$'$13.5$''$  & $-$53$^{\circ}$21$'$40$''$ & 8.46 & 4.7 & 5.1 $\times$ 10$^{7}$ & 1.9$'$ $\times$ 1.4$'$\\
Haro~11 &  00h36$'$52.5$''$ & $-$33$^{\circ}$33$'$19$''$ & 7.9 & 92 & $\sim$10$^{8}$ & 0.5$'$ $\times$ 0.5$'$ \\
Mrk~1089 &  05h01$'$37.8$''$ & $-$04$^{\circ}$15$'$28$''$ & 8.0 & 59.8 & 2.7 $\times$ 10$^{10}$ & 0.61$'$ $\times$ 0.23$'$ \\
UM~311 & 01h15$'$34$''$  & $-$00$^{\circ}$51$'$32$''$ & 8.3 & 21.3 & 2.3 $\times$ 10$^{9}$ & 0.11$'$ $\times$ 0.11$'$ \\
\hline
\end{tabular}}
\medskip
$^a$ References for metallicities: NGC~1705: \citet{Meurer1992}, Haro~11: \citet{Bergvall_Ostlin_2002}, Mrk~1089 and UM~311:  \citet{Hopkins2002}. \\
$^b$~References for distances: NGC~1705: \citet{Meurer1992}, Haro~11: \citet{Bergvall2000}, Mrk~1089 and UM~311: \citet{Hopkins2002}. \\
$^c$~References for the HI mass: NGC~1705: 8.9~$\times$ 10$^7$~\msun\ for $D$~= 6.2~Mpc \citep{Meurer1998}, Haro~11: upper limit derived from the HI~detection \citep{Bergvall_Ostlin_2002}, Mrk~1089: 2.1 $\times$ 10$^{10}$ \msun\ for $D=53$~Mpc \citep{Williams1991}, UM~311: 3.1 $\times$ 10$^9$~\msun\ for $D$~= 24.7~Mpc \citep{Smoker2000}. The HI~masses were scaled according to the distances we~used.
\end{table}