Dwarf spheroidal galaxies in the M81 group imaged with WFPC2

We obtained HST/WFPC2 images of the dwarf spheroidal (dSph) galaxies K61, K 63, K64, DDO78, BK6N, and kk77 in the M81 group. Our color-magnitude diagra ms show red giant branches with tips (TRGB) falling within the range of I = [23.8 - 24.0] mag. The derived true distance moduli (DM) of the 6 dSphs ra nging from 27.71 to 27.93 mag are consistent with their membership in the g roup. Given accurate distances of 5 other group members, which have been de rived via TRGB or cepheids, the mean DM of the M81 group is (27.84 +/- 0.05 ) mag. We find the difference of the mean distances to the M81 and NGC 2403 groups to be D-M81 - D-NGC2403 = (0.5 + 0.2) Mpc, which yields a deproject ed separation of 0.9 Mpc. With respect to the Local group, M81 and NGC 2403 have radial velocities of 106 and 267 km s(-1) respectively, while the vel ocities of the group centroids are 142 and 281 km s(-1). The higher velocit y of the closer system may indicate that these groups are moving towards ea ch other, similar to the Milky Way and M31 in the Local group. Several glob ular cluster candidates have been identified in the galaxies.