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Description
BVRI/CCD photometry of ~2,300 stars in the central 2.2'x3.5' area of the dwarf elliptical galaxy NGC205 in the Local Group is presented. The color-magnitude diagrams of NGC 205 show: (1) a blue plume around (B-V)~0.0mag, extending up to V~19.3mag (M_V_~-5.4mag); and (2) a strong asymptotic giant branch (AGB) population, the brightest of which reaches I~19.0mag, 1.5 mag brighter than the tip of the red giant branch. BVRI photometry of three globular clusters (Hubble IV. V, and VI) is also presented. Hubble V is much bluer [(B-V)=0.37] than other globular clusters. This blue color of Hubble V leads to an estimate of the age, ~300Myrs. A V luminosity function for the blue stars has been derived: the logarithmic slope of the luminosity function for -5.7<M_V_<-3.2 is 0.64+/-0.12, which is similar to those of other nearby galaxies. The AGB stars extend to Mbol~-5.7mag, which is ~0.7mag brighter than those in NGC 185. The bolometric luminosity function of the AGB stars in NGC 205 is found to be flatter than that of the similar dwarf elliptical galaxy NGC 185, but similar to that of a bulge field 4' of the nucleus of M31. Surface photometry for the central area within R=50" is presented, showing that the colors get bluer as the galactocentric radius decreases except for the nucleus region within R=1.6" where the colors get redder inward. Star formation history in NGC 205 is briefly discussed.
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