Abstract
ABSmACT. Photoel ect rio UBVRI ( ins) photane try is reported for thirty stars in the field of the galactic cluster NGC7790. The pho tanetry was obtained with a pulse counting photaneter coupled with the 1.5 m telescope at San Pedro Observatory of National University of Mexico. An analysis of the color-color and color-magnitude diagrams peunitted the identification of sane peculiar stars that may not be menbers of the cluster. By canputing the Q-parameter for each cluster , an average reddening was estimated to be E(wv)=O.62+O.08. No evidence of differential reddening was found. The Main Sequence fitting method was nployed to estimate the true distance modulus (V- )0 = 12. 40i0. 30. The adopted Main Sequence was that of Pedreros (1984, Ph. D. Thesis University of Toronto). Our results are in good agreernent with those of Pedreros et al. (1984, Ap. J., 286, 563). The absolute magnItudes of the cluster cepheids CF CAS, CE GASa, CE CASb have been determined fran the obtained color excess and the true distance modulus. Our results are: Cepheid Mv CE CASa -3.43 CE CASb -3.36 CE GAS -3.23 These values of the absolute magnitudes are reproduced by the period-luminosity and period-luminosity-color relationships of Scbrriidt (1984, Ap. J. 285, 501) within 0.1 magnitudes. Details and further discussion will be published as a paper elsewhere. Kay WOJt : CLUSTERS-OPEN -- DISTANCES -- STARS-CEPHEID
