Data sources:
(systematical corrections were taken into account)

A5:UBVRc observations by V.P.Goranskij with the SAI Crimean Station 50-cm Maksutov meniscus telescope AZT-5 and CCD Apogee Alta U8300 [V=V(A5)+0.04];
AA: CCD V monitoring with the 50-cm Maksutov telescope of SAI Crimean Station and Apogee Alta F8300 CCD;
BM: Yu.K.Bergner, A.S.Miroshnichenko, R.V.Yudin, K.S.Kuratov, D.V.Mukanov, T.A.Shejkina, Astron. & Astrophys. Suppl. Series V.112, 221, 1995;
C6/C7/Pi/A7/47/VA/VJ: CCD UBVRcRj photometry made with SBIG ST6, ST7, Meade Pictor-416, Apogee-7, Apogee-47, PI VersArray devices and different filter sets at 60-cm, 125-cm reflectors and 50-cm Maksutov telescope of SAI Crimean Station;
GB: M.R.Garcia, P.Berlind, E.Barton, J.E.McClintock, IAU Circ. 6865, 1998;
HM: A.Henden, U.Munari, Baltic Astronomy V.17, 293, 2008;
Hy: R.I.Hynes, P.Roche, C.A.Haswell, J.Telting, M.Lehnert, Y.Simis, IAU Circ 6871, 1998;
Me: UBV photometry by N.V.Metlova with the Lyuty's photoelectric photometer and 60-cm Zeiss telescope of SAI Crimean Station (partly published in Astr. Rep. V46, 275, 2002).
MM: V.P.Goranskij with the SAO 1-m Zeiss Telescope and the MMPP photometer polarimeter.
SH: CCD V photometry made with ST10MXE and 50-cm reflector of Stara Lesna Observatory (Slovakia);
OP: M.Orlandini, A.N.Parmar, F.Frontera, N.Masetti, D.Dal Fiume, A.Orr, A.Piccioni, G.Raimondo, A.Santanegro, G.Valentini, T.Belloni, Astron. & Astrophys. V.356, 163, 2000;
RW: E.L.Robinson, W.F.Welch, M.T.Adams, M.E.Cornell, IAU Circ 6862, 1988;
Sh/f7: UBV and BVRj photometry by V.P.Goranskij, S.Yu.Shugarov and E.A.Karitskaya with the Shugarov-Volkov photoelectric photometer at 70-cm telescope of SAI in Moscow (partly published in Astr. Rep.V46, 275, 2002);
SO: CCD UBVRc photometry made with Electronika K-585 and EEV 42-40 chips and different filter sets at 1-m Zeiss of the Special Astrophysical Observatory.

CL,Cr,SP,TS: other unclarified sources;
XM: XMM Guide Sensor.