| New JHK photometry has been obtained for Cepheid variables in the LMC and SMC bringing the total number of JHK observation sets to 291 for 68 stars in LMC and 183 for 94 stars in the SMC. From this sample, intensity-weighted mean magnitudes are derived for 52 LMC and 90 SMC classical Cepheids. J, H, and K period-luminosity relations have been determined for the LMC and SMC which show no significant difference in slope. True distance moduli of 18.46 (+OR-) 0.05 and 18.97 (+OR-) 0.05 mag are found for the LMC and SMC, respectively, based on the calibration of Welch et al. (1985). Magnitude residuals from the JHK period-luminosity relations are shown to correlate with position on the sky, indicating a gradient in depth of 0.014 mag/deg in right ascension. The discovery of K-excesses in three Type II Cepheids is also reported.; The distance to M31 (NGC 224) has been determined using H photometry of seven classical Cepheids in Fields III and IV. Identification of contaminated photometry is described. Uncontaminated observations have been reduced to intensity-weighted mean magnitudes. Using the Galactic calibration of Welch et al. (1985) and mean H magnitudes of 52 LMC Cepheids, a weighted least-squares solution for the H P-L relation results in an apparent distance modulus of (m - M)(,H) = 24.31 (+OR-) 0.08 mag. Using our best estimate of A(,H) = 0.05 (+OR-) 0.02 mag, we obtain a true distance modulus of (m - M)(,0) = 24.26 (+OR-) 0.08 mag. Astrometry for 82 Cepheids in Fields I, II, III, and IV is also presented.; Maximum-likelihood radius determinations for five short-period Galactic Cepheids (SS Sct, V350 Sgr, BB Sgr, U Sgr, V496 Aql) have been obtained using V and K magnitudes, color indices (B - V) and (V - R(,KC)), and contemporaneous radial velocity curves. It is shown that radii are better determined in the infrared for photometry of the same quality. A technique for obtaining uncertainties from maximum likelihood solutions is also described. |
