\begin{table}%t6 \caption{Parameters of VLBA water maser features in core C. For each identified feature, Col.~1 indicates the harboring maser subcluster; Cols.~2 and~3 the LSR velocity and the integrated flux density of the highest-intensity channel; Cols.~4 and~5 the positional (RA and Dec) offsets (with the associated errors), evaluated with respect to the derived absolute position of the reference feature ($\alpha(J2000) = 18^{\rm h} 36^{\rm m} 13\fs1140$, $\delta(J2000) = -7\degr 12' 7\farcs528$); Cols.~6--8 the projected components along the RA and Dec axes and the absolute value of the derived proper motions (together with the associated errors).}\label{wat_coreC} %\centering \small \begin{tabular}{cccccccccc} \hline\hline Cluster & $V_{\rm LSR}$ & $F_{\rm int}$ & & $\Delta \alpha$ ~ ~ ~ & $\Delta \delta$ ~ ~ ~ & & $V_{x}$ & $V_{y}$ & $V_{\rm mod}$ \\ & (km s$^{-1}$) & (Jy) & & (mas) ~ ~ & (mas) ~ ~ & & (km s$^{-1}$) & (km s$^{-1}$) & (km s$^{-1}$) \\ \hline C1 & 114.5 & 4.8 & & $0.0 \pm 0.2$ & $0.0 \pm 0.2$ & & $-80 \pm 9$ & $-101 \pm 9$ & $129 \pm 9$ \\ C1 & 114.7 & 1.5 & & $162.4 \pm 0.2$ & $241.3 \pm 0.2$ & & $-55 \pm 10$ & $-153 \pm 10$ & $163 \pm 10$ \\ C1 & 110.8 & 1.3 & & $81.2 \pm 0.2$ & $87.0 \pm 0.2$ & & & & \\ C1 & 107.7 & 1.1 & & $41.2 \pm 0.2$ & $33.5 \pm 0.2$ & & & & \\ C1 & 115.1 & 0.8 & & $163.3 \pm 0.2$ & $242.6 \pm 0.2$ & & $-18 \pm 18$ & $-76 \pm 19$ & $78 \pm 19$ \\ C1 & 116.7 & 0.8 & & $18.6 \pm 0.2$ & $-8.4 \pm 0.2$ & & $-49 \pm 18$ & $-68 \pm 19$ & $84 \pm 18$ \\ C1 & 114.2 & 0.3 & & $165.9 \pm 0.2$ & $254.2 \pm 0.2$ & & & & \\ C1 & 114.1 & 0.3 & & $166.0 \pm 0.2$ & $249.1 \pm 0.2$ & & & & \\ C1 & 116.5 & 0.2 & & $157.6 \pm 0.2$ & $238.3 \pm 0.2$ & & $-51 \pm 18$ & $-93 \pm 19$ & $107 \pm 19$ \\ C1 & 117.9 & 0.2 & & $55.1 \pm 0.2$ & $-10.7 \pm 0.2$ & & & & \\ C1 & 107.6 & 0.1 & & $58.7 \pm 0.2$ & $-22.5 \pm 0.2$ & & & & \\ C1 & 121.5 & 0.1 & & $150.0 \pm 0.2$ & $257.0 \pm 0.2$ & & & & \\ C1 & 123.8 & 0.07 & & $150.4 \pm 0.2$ & $258.1 \pm 0.2$ & & & & \\ C1 & 127.1 & 0.06 & & $150.0 \pm 0.2$ & $290.2 \pm 0.2$ & & & & \\ C1 & 107.2 & 0.06 & & $40.6 \pm 0.2$ & $37.9 \pm 0.2$ & & & & \\ & & & & & & & & & \\ C2 & 102.3 & 1.6 & & $20.5 \pm 0.2$ & $372.7 \pm 0.2$ & & & & \\ C2 & 105.0 & 1.6 & & $18.4 \pm 0.2$ & $370.5 \pm 0.2$ & & & & \\ C2 & 124.6 & 1.0 & & $59.6 \pm 0.2$ & $361.6 \pm 0.2$ & & $-24 \pm 14$ & $-178 \pm 14$ & $180 \pm 14$ \\ C2 & 119.3 & 0.9 & & $52.0 \pm 0.2$ & $365.2 \pm 0.2$ & & $-15 \pm 11$ & $-139 \pm 10$ & $140 \pm 10$ \\ C2 & 124.2 & 0.9 & & $63.5 \pm 0.2$ & $357.3 \pm 0.3$ & & & & \\ C2 & 107.3 & 0.9 & & $18.4 \pm 0.2$ & $372.5 \pm 0.2$ & & & & \\ C2 & 109.2 & 0.8 & & $17.7 \pm 0.2$ & $370.5 \pm 0.2$ & & & & \\ C2 & 125.5 & 0.7 & & $59.2 \pm 0.2$ & $361.8 \pm 0.2$ & & & & \\ C2 & 125.3 & 0.7 & & $63.5 \pm 0.2$ & $357.4 \pm 0.2$ & & $0 \pm 14$ & $-199 \pm 14$ & $199 \pm 14$ \\ C2 & 101.1 & 0.5 & & $16.1 \pm 0.2$ & $372.7 \pm 0.2$ & & & & \\ C2 & 103.4 & 0.5 & & $29.5 \pm 0.2$ & $364.6 \pm 0.2$ & & $25 \pm 19$ & $-94 \pm 20$ & $98 \pm 20$ \\ C2 & 120.6 & 0.4 & & $62.6 \pm 0.2$ & $359.6 \pm 0.2$ & & & & \\ C2 & 94.9 & 0.4 & & $20.0 \pm 0.2$ & $372.7 \pm 0.2$ & & & & \\ C2 & 98.4 & 0.4 & & $19.5 \pm 0.2$ & $373.0 \pm 0.2$ & & & & \\ C2 & 96.3 & 0.4 & & $18.1 \pm 0.2$ & $373.4 \pm 0.2$ & & $-127 \pm 10$ & $-84 \pm 12$ & $152 \pm 11$ \\ C2 & 124.0 & 0.3 & & $60.4 \pm 0.2$ & $361.0 \pm 0.2$ & & $-1 \pm 14$ & $-190 \pm 15$ & $190 \pm 15$ \\ C2 & 90.8 & 0.3 & & $29.7 \pm 0.2$ & $366.0 \pm 0.2$ & & & & \\ C2 & 103.2 & 0.3 & & $19.1 \pm 0.2$ & $372.4 \pm 0.2$ & & $-97 \pm 18$ & $26 \pm 19$ & $101 \pm 18$ \\ C2 & 97.5 & 0.3 & & $19.7 \pm 0.2$ & $370.1 \pm 0.2$ & & & & \\ C2 & 121.7 & 0.3 & & $63.2 \pm 0.2$ & $358.9 \pm 0.2$ & & & & \\ C2 & 101.6 & 0.3 & & $16.8 \pm 0.2$ & $372.5 \pm 0.2$ & & & & \\ C2 & 108.0 & 0.2 & & $20.3 \pm 0.2$ & $372.6 \pm 0.2$ & & & & \\ C2 & 106.5 & 0.2 & & $18.0 \pm 0.2$ & $367.3 \pm 0.2$ & & & & \\ C2 & 108.7 & 0.2 & & $16.3 \pm 0.2$ & $371.1 \pm 0.2$ & & & & \\ C2 & 106.0 & 0.2 & & $18.2 \pm 0.2$ & $374.0 \pm 0.2$ & & & & \\ C2 & 100.5 & 0.2 & & $18.0 \pm 0.2$ & $372.4 \pm 0.2$ & & & & \\ C2 & 124.9 & 0.2 & & $62.5 \pm 0.2$ & $356.8 \pm 0.2$ & & & & \\ C2 & 97.8 & 0.1 & & $15.0 \pm 0.2$ & $368.9 \pm 0.2$ & & & & \\ C2 & 106.8 & 0.1 & & $19.7 \pm 0.2$ & $372.7 \pm 0.2$ & & & & \\ C2 & 125.7 & 0.1 & & $62.7 \pm 0.2$ & $358.8 \pm 0.2$ & & & & \\ C2 & 97.1 & 0.1 & & $3.3 \pm 0.2$ & $385.1 \pm 0.2$ & & & & \\ C2 & 126.5 & 0.1 & & $63.8 \pm 0.2$ & $355.5 \pm 0.2$ & & & & \\ C2 & 91.4 & 0.09 & & $17.5 \pm 0.2$ & $372.5 \pm 0.3$ & & & & \\ C2 & 95.1 & 0.08 & & $-1.3 \pm 0.2$ & $382.9 \pm 0.2$ & & & & \\ C2 & 119.6 & 0.07 & & $61.3 \pm 0.2$ & $361.2 \pm 0.2$ & & & & \\ C2 & 107.9 & 0.05 & & $17.4 \pm 0.2$ & $373.1 \pm 0.2$ & & & & \\ & & & & & & & & & \\ C3 & 54.0 & 59.9 & & $-161.0 \pm 0.2$ & $364.7 \pm 0.2$ & & $-39 \pm 20$ & $-74 \pm 20$ & $84 \pm 20$ \\ C3 & 60.8 & 16.4 & & $-160.0 \pm 0.2$ & $366.9 \pm 0.2$ & & $-58 \pm 10$ & $-123 \pm 11$ & $136 \pm 11$ \\ C3 & 48.9 & 11.8 & & $-161.8 \pm 0.2$ & $364.0 \pm 0.2$ & & & & \\ C3 & 56.3 & 7.2 & & $-160.7 \pm 0.2$ & $366.8 \pm 0.2$ & & $-61 \pm 15$ & $-193 \pm 16$ & $202 \pm 16$ \\ C3 & 57.2 & 6.0 & & $-161.0 \pm 0.2$ & $365.2 \pm 0.2$ & & & & \\ C3 & 73.0 & 4.0 & & $-163.0 \pm 0.2$ & $380.2 \pm 0.2$ & & & & \\ C3 & 43.8 & 3.1 & & $-161.4 \pm 0.2$ & $365.3 \pm 0.2$ & & & & \\ C3 & 96.9 & 2.4 & & $-215.6 \pm 0.2$ & $410.3 \pm 0.2$ & & $-68 \pm 10$ & $-148 \pm 10$ & $163 \pm 10$ \\ \hline C3 & 43.0 & 2.4 & & $-160.5 \pm 0.2$ & $365.9 \pm 0.2$ & & & & \\ C3 & 57.1 & 2.3 & & $-161.5 \pm 0.2$ & $364.1 \pm 0.2$ & & & & \\ C3 & 97.0 & 1.6 & & $-215.1 \pm 0.2$ & $405.9 \pm 0.2$ & & & & \\ C3 & 83.1 & 1.4 & & $-212.6 \pm 0.2$ & $409.5 \pm 0.2$ & & & & \\ C3 & 48.8 & 1.2 & & $-161.8 \pm 0.2$ & $364.8 \pm 0.2$ & & $-67 \pm 14$ & $-177 \pm 14$ & $190 \pm 14$ \\ C3 & 44.0 & 1.0 & & $-160.1 \pm 0.2$ & $366.3 \pm 0.2$ & & & & \\ C3 & 47.9 & 0.9 & & $-162.3 \pm 0.2$ & $366.5 \pm 0.2$ & & $-53 \pm 14$ & $-151 \pm 15$ & $160 \pm 15$ \\ C3 & 94.8 & 0.9 & & $-216.5 \pm 0.2$ & $406.7 \pm 0.2$ & & & & \\ C3 & 39.5 & 0.8 & & $-161.4 \pm 0.2$ & $365.6 \pm 0.2$ & & & & \\ C3 & 96.0 & 0.8 & & $-216.9 \pm 0.2$ & $407.1 \pm 0.2$ & & & & \\ C3 & 109.6 & 0.8 & & $-161.4 \pm 0.2$ & $371.7 \pm 0.2$ & & & & \\ C3 & 109.9 & 0.8 & & $-536.0 \pm 0.2$ & $629.0 \pm 0.2$ & & & & \\ C3 & 88.1 & 0.7 & & $-161.0 \pm 0.2$ & $374.1 \pm 0.2$ & & & & \\ C3 & 37.8 & 0.7 & & $-160.7 \pm 0.2$ & $366.8 \pm 0.2$ & & & & \\ C3 & 58.2 & 0.6 & & $-162.8 \pm 0.2$ & $361.7 \pm 0.2$ & & & & \\ C3 & 56.1 & 0.6 & & $-158.8 \pm 0.2$ & $368.6 \pm 0.2$ & & $-52 \pm 19$ & $-114 \pm 23$ & $126 \pm 22$ \\ C3 & 100.1 & 0.5 & & $-216.8 \pm 0.2$ & $410.9 \pm 0.2$ & & $-67 \pm 14$ & $-181 \pm 17$ & $193 \pm 17$ \\ C3 & 71.0 & 0.5 & & $-215.6 \pm 0.2$ & $412.4 \pm 0.2$ & & $-62 \pm 14$ & $-162 \pm 14$ & $174 \pm 14$ \\ C3 & 116.6 & 0.5 & & $-160.1 \pm 0.2$ & $365.3 \pm 0.2$ & & & & \\ C3 & 105.2 & 0.5 & & $-159.2 \pm 0.2$ & $367.1 \pm 0.2$ & & & & \\ C3 & 58.0 & 0.4 & & $-160.4 \pm 0.2$ & $365.1 \pm 0.2$ & & & & \\ C3 & 99.6 & 0.3 & & $-159.8 \pm 0.2$ & $366.1 \pm 0.2$ & & & & \\ C3 & 34.6 & 0.3 & & $-161.0 \pm 0.2$ & $368.0 \pm 0.2$ & & & & \\ C3 & 98.1 & 0.3 & & $-211.9 \pm 0.2$ & $410.9 \pm 0.2$ & & $-26 \pm 18$ & $-96 \pm 19$ & $99 \pm 19$ \\ C3 & 64.4 & 0.3 & & $-160.5 \pm 0.2$ & $366.5 \pm 0.2$ & & & & \\ C3 & 95.4 & 0.3 & & $-214.0 \pm 0.2$ & $409.0 \pm 0.2$ & & $-52 \pm 14$ & $-199 \pm 14$ & $205 \pm 14$ \\ C3 & 76.7 & 0.3 & & $-176.3 \pm 0.2$ & $390.4 \pm 0.2$ & & & & \\ C3 & 42.1 & 0.3 & & $-163.0 \pm 0.2$ & $365.8 \pm 0.2$ & & & & \\ C3 & 52.1 & 0.3 & & $-162.5 \pm 0.2$ & $362.1 \pm 0.2$ & & & & \\ C3 & 70.3 & 0.2 & & $-162.4 \pm 0.2$ & $359.9 \pm 0.2$ & & & & \\ C3 & 49.9 & 0.2 & & $-164.8 \pm 0.2$ & $366.0 \pm 0.2$ & & & & \\ C3 & 80.4 & 0.2 & & $-214.9 \pm 0.2$ & $409.6 \pm 0.2$ & & & & \\ C3 & 96.9 & 0.2 & & $-216.8 \pm 0.2$ & $411.4 \pm 0.2$ & & & & \\ C3 & 42.0 & 0.2 & & $-162.6 \pm 0.2$ & $365.3 \pm 0.2$ & & & & \\ C3 & 74.0 & 0.2 & & $-175.8 \pm 0.2$ & $390.1 \pm 0.2$ & & & & \\ C3 & 68.3 & 0.2 & & $-162.8 \pm 0.2$ & $379.9 \pm 0.2$ & & & & \\ C3 & 87.7 & 0.2 & & $-182.0 \pm 0.2$ & $392.3 \pm 0.2$ & & & & \\ C3 & 68.9 & 0.2 & & $-161.4 \pm 0.2$ & $364.2 \pm 0.2$ & & & & \\ C3 & 54.8 & 0.2 & & $-162.5 \pm 0.2$ & $361.7 \pm 0.2$ & & & & \\ C3 & 82.7 & 0.2 & & $-215.9 \pm 0.2$ & $412.6 \pm 0.2$ & & & & \\ C3 & 45.3 & 0.2 & & $-162.5 \pm 0.2$ & $365.5 \pm 0.2$ & & & & \\ C3 & 105.6 & 0.2 & & $-160.3 \pm 0.2$ & $365.6 \pm 0.2$ & & & & \\ C3 & 39.5 & 0.1 & & $-161.4 \pm 0.2$ & $366.7 \pm 0.2$ & & & & \\ C3 & 97.7 & 0.1 & & $-215.8 \pm 0.2$ & $406.0 \pm 0.2$ & & & & \\ C3 & 84.5 & 0.1 & & $-182.5 \pm 0.2$ & $410.0 \pm 0.2$ & & & & \\ C3 & 43.4 & 0.1 & & $-163.3 \pm 0.2$ & $363.5 \pm 0.2$ & & & & \\ C3 & 52.6 & 0.1 & & $-165.3 \pm 0.2$ & $366.9 \pm 0.2$ & & & & \\ C3 & 83.5 & 0.1 & & $-214.7 \pm 0.2$ & $411.0 \pm 0.2$ & & & & \\ C3 & 78.5 & 0.1 & & $-163.3 \pm 0.2$ & $380.6 \pm 0.2$ & & & & \\ C3 & 48.0 & 0.1 & & $-162.0 \pm 0.2$ & $364.3 \pm 0.2$ & & & & \\ C3 & 50.6 & 0.1 & & $-160.9 \pm 0.2$ & $365.9 \pm 0.2$ & & & & \\ C3 & 38.0 & 0.08 & & $-161.3 \pm 0.2$ & $365.9 \pm 0.2$ & & & & \\ C3 & 105.5 & 0.08 & & $-161.2 \pm 0.2$ & $306.5 \pm 0.2$ & & & & \\ C3 & 82.2 & 0.07 & & $-216.7 \pm 0.2$ & $428.4 \pm 0.2$ & & & & \\ C3 & 90.1 & 0.06 & & $-212.3 \pm 0.2$ & $412.8 \pm 0.2$ & & & & \\ C3 & 53.8 & 0.05 & & $-169.6 \pm 0.2$ & $399.3 \pm 0.2$ & & & & \\ C3 & 62.4 & 0.05 & & $-163.6 \pm 0.2$ & $376.3 \pm 0.2$ & & & & \\ C3 & 85.2 & 0.04 & & $-421.3 \pm 0.2$ & $715.4 \pm 0.3$ & & & & \\ \hline \end{tabular} \end{table}