We have obtained HST WFPC2 and ground-based images of two low surface brightness dwarf spheroidal galaxies in the M81 group , FM1 and KKH57 .
Their colour-magnitude diagrams show red giant branches with tips at I = 23.77 \pm 0.14 and I = 23.97 \pm 0.17 , respectively .
The derived true distance moduli , 27.66 \pm 0.16 and 27.96 \pm 0.19 , agree well with the mean distance modulus of the M81 group , 27.84 \pm 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 ( \Sigma _ { 0 ,V } = 24.8 and 24.4 mag/ \squareforqed \arcsec ) are in the range of other dSph companions of M81 , M31 , and Milky Way .
With two new objects the maximum projected radius of the dwarf spheroidal subsystem around M81 is 380 kpc .