\begin{table}%t9 \caption{\label{Grt_correl}Remarkable or interesting correlations of computed spectral gradients.} \small%\centerline { \begin{tabular}{c c c c c c c c c c c} \hline\hline & & & OWN & & & OWN+LP & & & OWN+LP+2MS &\\ & correlated magnitudes & $\rho$ & SL(\%) & $n$ & $\rho$ & SL(\%) & $n$ & $\rho$ & SL(\%) & $n$\\ \hline Classicals & Grt vs. $i$ & $-$0.28 & 77.11 & 19 & $-$0.49 & 99.95 & 52 & $-$0.47 & 99.99 & 73 \\ & Grt vs. $i$ ($H_{R}>6.2$) & $-$0.68 & 90.35 & 7 & $-$0.61 & 99.94 & 33 & $-$0.66 & 99.99 & 38 \\ & Grt vs. $i$ ($H_{R}<6.2$) & $-$0.17 & 42.29 & 12 & $-$0.37 & 88.47 & 19 & $-$0.36 & 96.48 & 35 \\ & Grt vs. $\psi$& 0.12 & 37.68 & 19 & $-$0.03 & 16.76 & 52 & $-$0.08 & 48.26 & 73 \\ & Grt vs. $\psi$ ($H_{R}>6.2$) & $-$0.14 & 27.36 & 7 & 0.13 & 55.39 & 33 & 0.16 & 66.45 & 38 \\ & Grt vs. $\psi$ ($H_{R}<6.2$) & $-$0.20 & 49.88 & 12 & $-$0.41 & 91.71 & 19 & $-$0.40 & 97.90 & 35 \\ \hline Hot & Grt vs. $Q$ & $-$0.24 & 52.17 & 10 & $-$0.04 & 17.01 & 27 & $-$0.03 & 16.00 & 42 \\ & Grt vs. $Q$ ($H_{R}>6.2$) & $-$0.40 & 51.16 & 4 & $-$0.30 & 75.93 & 16 & $-$0.32 & 83.34 & 20 \\ & Grt vs. $Q$ ($H_{R}<6.2$) & 0.26 & 43.47 & 6 & 0.54 & 91.01 & 11 & 0.40 & 93.34 & 22 \\ & Grt vs. $a$ & $-$0.08 & 18.68 & 10 & 0.11 & 40.76 & 27 & 0.21 & 81.33 & 42 \\ & Grt vs. $a$ ($H_{R}>6.2$) & $-$0.40 & 51.16 & 4 & $-$0.16 & 46.90 & 16 & $-$0.09 & 30.59 & 20 \\ & Grt vs. $a$ ($H_{R}<6.2$) & 0.66 & 85.83 & 6 & 0.61 & 94.59 & 11 & 0.57 & 99.12 & 22 \\ \hline SDOs & Grt vs. $e$ & $-$0.32 & 62.96 & 9 & $-$0.49 & 96.28 & 19 & $-$0.27 & 81.78 & 25 \\ & Grt vs. $H_{R}$ & $-$0.52 & 85.61 & 9 & $-$0.64 & 99.34 & 19 & $-$0.34 & 90.86 & 25 \\ \hline Cent & Grt vs. $i$ & & & & $-$0.31 & 67.16 & 11 & $-$0.31 & 79.67 & 18 \\ & Grt vs. $e$ & & & & 0.39 & 78.36 & 11 & 0.56 & 98.01 & 18 \\ & Grt vs. $H_{R}$ & & & & $-$0.51 & 89.26 & 11 & $-$0.26 & 72.21 & 18 \\ \hline All & Grt vs. $q$ & 0.13 & 52.26 & 30 & 0.32 & 99.66 & 83 & 0.34 & 99.97 & 116 \\ & Grt vs. $i$ & $-$0.47 & 98.78 & 30 & $-$0.48 & 100.00 & 83 & $-$0.42 & 100.00 & 116 \\ & Grt vs. $e$ & $-$0.28 & 86.45 & 30 & $-$0.28 & 98.85 & 83 & $-$0.27 & 99.68 & 116 \\ & Grt vs. $H_{R}$ & $-$0.63 & 99.93 & 30 & $-$0.28 & 98.91 & 83 & $-$0.17 & 93.72 & 116 \\ \hline SDOs+hot & Grt vs. $q$ & $-$0.03 & 9.48 & 19 & 0.31 & 96.06 & 46 & 0.38 & 99.78 & 66 \\ & Grt vs. $i$ & $-$0.41 & 91.73 & 19 & $-$0.37 & 98.75 & 46 & $-$0.27 & 97.13 & 66 \\ & Grt vs. $H_{R}$ & $-$0.57 & 98.38 & 19 & $-$0.40 & 99.21 & 46 & $-$0.26 & 96.39 & 66 \\ \hline SDOs+Cent & Grt vs. $H_{R}$ & $-$0.65 & 94.83 & 10 & $-$0.48 & 99.02 & 30 & $-$0.19 & 76.87 & 42 \\ \hline \end{tabular}} \medskip Interesting correlations of the spectral gradient (Grt) versus~$H_{R}$ and orbital parameters discussed in text. The spectral gradient, Grt(\%$/100$~nm), was calculated by fitting over the available color intervals per object. OWN means our own data, OWN+LP means our own data merged with the ESO Large Program data (Boehnhardt et~al. \cite{Boe02}; Peixinho et~al. \cite{Peix}), OWN+LP+2MS means the OWN+LP data merged with the Meudon Multicolor Survey data (Doressoundiram et~al. \cite{Doress_b}), $\rho$~= Spearman rank correlation, SL~= Significance level, $n$~= Number of objects. \end{table}