\begin{table}%t1 \caption{\label{members}Spectroscopic members of the structure around 7C~1756+6520.} %\centering \par {\fontsize{8.25pt}{10.25pt}\selectfont \begin{tabular}{l l l l c l c c c l} \hline\hline ID & Name\tablefootmark{a} & RA & Dec & $z_{\rm spec}$ & Q\tablefootmark{b} &$B$\tablefootmark{c} & $z$\tablefootmark{c} & $K$\tablefootmark{c} & Notes \\ & & (J2000) & (J2000) & & & (AB) & (AB) & (AB) & \\ \hline Cl~1756.1 & AGN.1110 & 17:56:52.56 & 65:16:56.65 & $1.3935\pm0.0012$ & B & $23.21$ & $22.14$ & $20.89$ & B$2900$, B$3260$, [OII] \\ Cl~1756.2 & s$BzK$.6355 & 17:57:59.55 & 65:18:00.64 & $1.4020\pm0.0001$ & A & $24.36$ & $23.34$ & $21.54$ & [OII] \\ Cl~1756.3 & s$BzK$.9622 & 17:57:21.75 & 65:23:05.04 & $1.4064\pm0.0005$ & A & $24.00$ & $22.78$ & $20.38$ & [OII] \\ Cl~1756.4 & s$BzK$.7556 & 17:57:46.54 & 65:20:00.48 & $1.4081\pm0.0007$ & A & $20.97$ & $20.77$ & $20.35$ & AGN: broad MgII, [OII] \\ Cl~1756.5 & p$BzK$.5858 & 17:57:44.40 & 65:17:14.30 & $1.4110\pm0.0010$ & B & $>$$27.1$ & $23.80$ & $21.62$ & [OII]; ID$31$ in G09 \\ Cl~1756.6 & serendip.1 & 17:56:57.67 & 65:18:49.45 & $1.4150\pm0.0005$ & A & -- & -- & -- & [OII] \\ Cl~1756.7\tablefootmark{d} & AGN.1354 & 17:57:04.98 & 65:19:51.00 & $1.4153\pm0.0003$ & B & $26.34$ & $22.03$ & -- & AGN: broad MgII \\ HzRG & 7C~1756+6520 & 17:57:05.48 & 65:19:53.75 & $1.4156\pm0.0001$ & A & $>$$27.1$ & $21.40$ & $20.17$ & AGN: [NeV], [OII], [NeIII] \\ Cl~1756.8 & serendip.2 & 17:57:25.00 & 65:19:04.83 & $1.4157\pm0.0010$ & A & $26.32$ & $24.34$ & $>$$23.4$ & [OII] \\ Cl~1756.9 & s$BzK$.6997 & 17:57:24.43 & 65:19:03.87 & $1.4157\pm0.0006$ & A & $25.21$ & $24.21$ & $22.56$ & [OII] \\ Cl~1756.10 & AGN.1317 & 17:56:55.75 & 65:19:07.00 & $1.4162\pm0.0005$ & A & $20.16$ & $19.46$ & $19.01$ & AGN: broad MgII, [NeV], [OII] \\ Cl~1756.11 & s$BzK$.7624 & 17:56:33.16 & 65:20:04.46 & $1.4236\pm0.0001$ & A & $22.51$ & $22.39$ & $21.30$ & FeII+MgII absn, [OII ] \\ Cl~1756.12\tablefootmark{e} & p$BzK$.7523 & 17:57:05.04 & 65:19:54.50 & $1.4244\pm0.0004$ & A & $>$$27.1$ & $23.47$ & $21.31$ & [OII]; ID$43$ in G09 \\ Cl~1756.13 & s$BzK$.5860 & 17:57:35.34 & 65:17:14.39 & $1.4268\pm0.0005$ & A & $22.96$ & $22.35$ & $21.31$ & AGN: broad MgII, [OII] \\ Cl~1756.14 & s$BzK$.5699 & 17:57:44.06 & 65:16:57.11 & $1.4274\pm0.0004$ & A & $25.89$ & $24.20$ & $22.71$ & [OII] \\ Cl~1756.15 & p$BzK$.10235 & 17:57:25.20 & 65:23:58.19 & $1.4277\pm0.0010$ & B & $>$$27.1$ & $23.45$ & $21.76$ & [OII]; ID$63$ in G09 \\ Cl~1756.16 & s$BzK$.4449 & 17:57:47.40 & 65:14:52.17 & $1.4326\pm0.0002$ & A & $24.93$ & $23.89$ & $23.02$ & [OII] \\ Cl~1756.17 & s$BzK$.7625 & 17:57:14.41 & 65:20:02.40 & $1.4366\pm0.0001$ & A & $>$$27.1$ & $24.46$ & $22.95$ & [OII] \\ Cl~1756.18 & AGN.1206 & 17:57:13.08 & 65:19:08.37 & $1.4371\pm0.0002$ & A & $>$$27.1$ & $>$$25.0$ & $21.49$ & [OII] \\ Cl~1756.19 & s$BzK$.7208 & 17:57:18.31 & 65:19:24.94 & $1.4374\pm0.0002$ & A & $24.93$ & $23.46$ & $22.00$ & [OII] \\ Cl~1756.20 & serendip.3 & 17:57:20.76 & 65:19:39.14 & $1.4379\pm0.0007$ & A & $25.29$ & $23.18$ & $21.50$ & [OII] \\ \hline \end{tabular}} \tablefoot{\tablefoottext{a}{The names are composed of the selection technique for the source -- AGN, s$BzK$ or p$BzK$ ($\equiv$p$BzK$* here) -- followed by the identification number in our $K$-band ($3.6~\mu$m) catalogue for $BzK$ (AGN) targets. Sources serendipitously identified are given a simple ``serendip.'' designation.} \tablefoottext{b}{Q indicates the quality of the redshift, either ``A'' indicating a highly certain redshift, or ``B'' indicating a high level of confidence (see Sect.~3.2).} \tablefoottext{c}{Magnitudes were derived using SExtractor MAG\_AUTO and are therefore slightly different from the aperture magnitudes used to derive colours for candidate selection.} \tablefoottext{d}{AGN found within $6\arcsec$ of 7C~1756+6520. No accurate magnitude is available in $K$ due to an artifact caused by a bright star in the near-infrared data. See Fig.~12 in G09.} \tablefoottext{e}{p$BzK$* galaxy found within $3\arcsec$ of 7C~1756+6520.}} \end{table}