THE BVRIJHK PERIOD-LUMINOSITY RELATIONS FOR GALACTIC CLASSICAL CEPHEIDS

Both the zero point and the slope of the period-luminosity relations f or the Johnson BVRI bands, the Kron-Cousins (RI)(c) bands, and the CIT JHK bands are obtained using nine Cepheids in seven Galactic open clu sters. The distances of the clusters are based on the Kholopov zero ag e main sequence, M(V)(B-V)(0). The scatter of the period-luminosity re lation decreases with the wavelength of the photometric band and is eq ual to only 0(m).05 for the K band. A procedure for the determination of the distance moduli of individual Cepheids is proposed; this algori thm provides an accuracy of 0(m).05 for observations in the BVK filter s or 0(m).07-0(m).09 if BVR, BVI, or BV measurements are used. The dis tance modulus of the LMC is estimated to be 18(m).25 +/- 0(m).05, in g ood agreement with the values inferred from RR Lyrae variables; red, s emi-regular, variable supergiants; and comparison of the linear and an gular expansion speeds for the shell of SN 1987 A.