Abstract

We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V ? 26.0 and I ? 24.7. We measure the red giant branch tip at I = 23.56 ± 0.10, and calculate a distance modulus of ?0 = 27.53 ± 0.12 (corresponding to a distance of 3.2 ± 0.2Mpc), placing UGC 4483 within the NGC 2403 subgroup. We were able to measure properties of a previously known young star cluster in UGC 4483, finding integrated magnitudes of V = 18.66 ± 0.21 and I = 18.54 ± 0.10 for the stellar contribution (integrated light minus Ha and [O III] contribution), corresponding to an age of ? 10-15 Myr and an initial mass of ? 104M?. This is consistent with the properties of the cluster's brightest stars, which were resolved in the data for the first time. Finally, a numerical analysis of the galaxy's stellar content yields a roughly constant star formation rate of 1.3 × 10-3 M? yr-1 and mean metallicity of [Fe/H] = -1.3dex from 15 Gyr ago to the present.