Abstract

We have obtained HST WFPC2 and ground-based images of two low surface brightness dwarf spheroidal galaxies in the M 81 group, FM1 and KKH57. Their colour-magnitude diagrams show red giant branches with tips at I = 23.77 ± 0.14 and I = 23.97 ± 0.17, respectively. The derived true distance moduli, 27.66 ± 0.16 and 27.96 ± 0.19, agree well with the mean distance modulus of the M 81 group, 27.84 ± 0.05. Absolute V magnitudes of the galaxies (-11.46 and -10.85), their colours ((B - V) = 0.88 and 0.80), and central surface brightnesses (?0,V = 24.8 and 24.4 mag/??) are in the range of other dSph companions of M 81, M 31, and Milky Way. With two new objects the maximum projected radius of the dwarf spheroidal subsystem around M 81 is 380 kpc.