WFPC2 observations of two dwarf spheroidal galaxies in the M 81 group

We have obtained HST WFPC2 and ground-based images of two low surface brigh tness dwarf spheroidal galaxies in the M 81 group, FM1 and KKH57. Their col our-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 modul us 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 su rface brightnesses (Sigma (0,V) = 24.8 and 24.4 mag/square") are in the ran ge of other dSph companions of M 81, M 31, and Milky Way. With two new obje cts the maximum projected radius of the dwarf spheroidal subsystem around M 81 is 380 kpc.