\begin{table}%t1%t2 \caption{\label{table:sites}Observing sites and equipment.} %\centering \par \begin{tabular}{r@{}lllrrrr@{}llccl} \hline\hline\noalign{\smallskip} \multicolumn{2}{c}{ID} & Observatory & Country & Longitude & Latitude & Altitude & \multicolumn{2}{l}{Telescope} & CCD camera/chip & FOV & Resolution & Filters\\ ~&~ & ~ & ~ & ~ & ~ & ~ & ~ & ~ & ~ &(arcmin$^2$) & (arcsec/pixel) & ~\\ \hline {\bf1}&~ & OAN-SPM & Mexico & 117.46\degr W & 31.04\degr N & 2776~m & 150-&cm & (Simultaneous $uvby$ photometer) & -- & -- & Str\"omgren $ubvy$\\ {\bf2}&{\bf a} & Baker & Missouri, USA & 93.04\degr W & 37.40\degr N & 418~m & 40-&cm & Apogee 7p & 6 $\times$ 6 & 0.35 & Johnson $V$\\ {\bf2}&{\bf b} & ~ & ~ & ~ & ~ & ~ & ~ & ~ & Roper Sci. 1340B & 12.1 $\times$ 11.7 & 0.54 & Johnson $BV$\\ {\bf3}&{\bf a} & ORM & La Palma, Spain & 17.88\degr W & 28.76\degr N & 2333~m & 120-&cm & EEV 40-42 (Merope) & 6.5 $\times$ 6.5 & 0.19 & Geneva-Cousins $UBV(I_{\rm C}$)\\ {\bf3}&{\bf b} & ~ & ~ & ~ & ~ & ~ & \multicolumn{2}{r}{(Mercator)} & P7 (photometer) & -- & -- & Geneva $UB_1BB_2V_1VG$\\ {\bf4}&~ & OFXB & Switzerland & 7.60\degr E & 46.20\degr N & 2200~m & 60-&cm & Apogee 47p & 20 $\times$ 20 & 1.15 & Johnson $BVI$\\ {\bf5}&~ & Michelbach & Austria & 15.76\degr E & 48.09\degr N & 636~m & 40-&cm & Apogee 6 & 26 $\times$ 26 & 1.52 & Johnson $BVI$\\ {\bf6}&~ & Vienna & Austria & 16.34\degr E & 48.23\degr N & 241~m & 80-&cm (vlt) & Apogee 7p & 14.3 $\times$ 9.5 & 0.56 & Johnson $BVI$\\ {\bf7}&~ & Bia{\l}k\'ow & Poland & 16.66\degr E & 51.47\degr N & 220~m & 60-&cm & Andor Tech. iKon DW432 & 12.9 $\times$ 11.9 & 0.62 & Johnson-Cousins $BV(I_{\rm C}$)\\ {\bf8}&~ & Athens & Greece & 23.78\degr E & 37.97\degr N & 250~m & 40-&cm & SBIG ST-8 & 15 $\times$ 10 & 0.59/1.77 & Bessell $VI$\\ {\bf9}&~ & EUO & Turkey & 27.28\degr E & 38.40\degr N & 795~m & 40-&cm & Apogee Alta & 9.2 $\times$ 9.2 & 0.54 & Bessell $BV$\\ {\bf10}&{\bf a} & TUG & Turkey & 30.34\degr E & 36.82\degr N & 2555~m & 150-&cm & Fairchild CCD447 (TFOSC) & 13.5 $\times$ 13.5 & 0.79 & Bessell $UBV$\\ {\bf10}&{\bf b} & ~ & ~ & ~ & ~ & ~ & 40-&cm (T40) & SBIG ST-8 & 13.8 $\times$ 9.2 & 0.54 & Bessell $BV$\\ {\bf11}&~ & Xinglong & China & 117.57\degr E & 40.40\degr N & 960~m & 50-&cm & VersArray 1300B & 22 $\times$ 22 & 1.00 & Johnson $V$\\ {\bf12}&~ & SOAO & South Korea & 128.46\degr E & 36.93\degr N & 1378~m & 61-&cm & SITe & 20.5 $\times$ 20.5 & 0.60 & Johnson-Cousins $BV(I_{\rm C}$)\\ \hline \end{tabular} \tablefoot {Observatory abbreviations and observers are: {\bf1}~-- OAN-SPM (Observatorio Astron\'omico Nacional de San Pedro M\'artir)~-- EP, KU; {\bf2}~-- Baker~-- MDR, JRE, GAG; {\bf3}~-- ORM (Observatorio del Roque de los Muchachos)~-- SS, JV, BA, CG, R{\O}, WDM, KY, MC, MSp, SP, VVH, WZ, RH, BV, DLa, EPA, TV, JDR, SD, MR, GD, EB, HVW, EV, CW, GR, YB, PD, JB, RD; {\bf4}~-- OFXB (Observatoire Fran{\c c}ois-Xavier-Bagnoud) -- SS; {\bf5}~-- Michelbach~-- ALe, PB, JP, LS; {\bf6}~-- Vienna~-- GH, ES, ALe, PL, DLo, BS; {\bf7}~-- Bia{\l}k\'ow~-- AP, AN, GK, MSt, ZK, GM; {\bf8}~-- Athens~-- PN, ALi; {\bf9}~-- EUO (Ege University Observatory)~-- KY, BK; {\bf10}~-- TUG (T\"ub\'itak National Observatory)~-- KY, BK; {\bf11}~-- Xinglong~-- JNF, CZ, XJJ; {\bf12}~-- SOAO (Sobaeksan Optical Astronomy Observatory)~-- S-LK, DHK, Y-JL, C-UL, J-HK.} \vspace*{3mm} \caption{\label{table:obs}Observations summary.} %\centering \par \begin{tabular}{r@{}lrrrrrrrrrrrrrc} \hline\hline\noalign{\smallskip} \multicolumn{2}{c}{ID} & Observatory & \multicolumn{2}{c}{Observing time} & \multicolumn{5}{c}{Number of frames} & \multicolumn{4}{c}{Precision (mmag)} & $\sigma_{{\rm amp},V}$ & PSF function\\ ~&~ & ~ & (nights) & (hours) & $U$ & $B$ & $V$ & $I$ & Total & $U$ & $B$ & $V$ & $I$ & (mmag) & ~\\ \hline {\bf1}&~ & OAN-SPM & 15 & 63.9 & -- & -- & -- & -- & -- & -- & -- & -- & -- & -- & -- \\ {\bf2}&{\bf a} & Baker & 1 & 1.8 & -- & -- & 111 & -- & 111 & -- & -- & 6.1 & -- & 1.03 & Penny 1 \\ {\bf2}&{\bf b} & ~ & 6 & 33.9 & -- & 2558 & 2564 & -- & 5122 & -- & 7.5 & 7.0 & -- & 0.25 & Moffat 25 \\ {\bf3}&{\bf a} & ORM & 135 & 399.0 & 2969 & 2968 & 2997 & 2932 & 11~866 & 3.8/6. 6 & 3.6/5.0 & 3.9/5.4 & 4.1/5.4 & 0.18 & Moffat 25 \\ {\bf3}&{\bf b} & ~ & 14 & 28.6 & -- & -- & -- & -- & -- & -- & -- & -- & -- & -- & -- \\ {\bf4}&~ & OFXB & 12 & 64.5 & -- & 1107 & 1133 & 1089 & 3329 & -- & 5.4 & 5.1 & 7.5 & 0.27 & Moffat 25 \\ {\bf5}&~ & Michelbach & 9 & 18.5 & -- & 479 & 476 & 475 & 1430 & -- & 7.8 & 4.8 & 5.7 & 0.39 & Gaussian \\ {\bf6}&~ & Vienna & 17 & 90.7 & -- & 4301 & 2140 & 3255 & 9696 & -- & 5.1 & 10 .7& 4.8 & 0.41 & Moffat 25 \\ {\bf7}&~ & Bia{\l}k\'ow & 71 & 287.7 & -- & 2830 & 12~438 & 5405 & 20~673 & -- & 2.6 & 3.0 & 3.8 & 0.05 & Moffat 25 \\ {\bf8}&~ & Athens & 8 & 24.3 & -- & -- & 967 & 970 & 1937 & -- & -- & 6.8/5.3 & 6.8/4.8 & 0.35 & Penny 2/Moffat 15\\ {\bf9}&~ & EUO & 3 & 13.0 & -- & 1244 & 1245 & -- & 2489 & -- & 5.7 & 6.3 & -- & 0.32 & Penny 2 \\ {\bf10}&{\bf a} & TUG & 2 & 8.8 & 106 & 101 & 105 & -- & 312 & 5.8 & 4.4 & 4.4 & -- & 0.76 & Moffat 25 \\ {\bf10}&{\bf b} & ~ & 3 & 14.7 & -- & 293 & 289 & -- & 582 & -- & 9.2 & 8.0 & -- & 0.83 & Penny 1 \\ {\bf11}&~ & Xinglong & 42 & 186.2 & -- & -- & 18~663 & -- & 18~663 & -- & -- & 4.7 & -- & 0.06 & Moffat 15 \\ {\bf12}&~ & SOAO & 13 & 50.7 & -- & 289 & 422 & 522 & 1233 & -- & 3.6 & 4.1 & 4.0 & 0.35 & Moffat 25 \\ \hline {\bf Total}&~ & ~ & 351 & 1286.3 & 3075 & 16~170 & 43~550 & 14~648 & 77~443 & 5.3 & 6.9 & 5.7 & 5.0 & 0.05 & ~ \\ \hline \end{tabular} \tablefoot {For ORM and Athens Observatory two precision numbers are noted. For ORM, these values refer to the first observation season on the one hand and to the second and third season on the other hand. For Athens Observatory, the two numbers refer to non-binned and binned images, respectively. $\sigma_{{\rm amp},V}$~= $\sigma_{V}\sqrt{\pi/{N}_{V}}$ denotes the noise in the amplitude spectrum of the $V$~light curve, and the PSF~function in the table is the analytical function we used to calculate the PSF~photometry in {\sc daophot}.} \end{table}