The problem of the relative motion of the substructures of the Local Group of galaxies revealed via S-tree method , as well as of the velocity of the Local Group itself , is considered .
The existence of statistically significant bulk flow of the Milky Way subsystem is shown via 3D reconstruction procedure , which uses the information on the radial velocities of the galaxies , but not on their distances .
Once the bulk motion of substructures is estimated , in combination with the observed CMB dipole we also consider the mean velocity of the Local Group itself .
Assigning the Local Group the mean motion of its main substructures we evaluate its peculiar velocity in Milky Way frame { V } _ { { LG } \rightarrow { MW } } = ( -7 \pm 303 , -15 \pm 155 , +177 \pm 144 ) or 178 km s ^ { -1 } toward galactic coordinates l = 245 and b = +85 .
Combined with CMB dipole { V } _ { { MW } \rightarrow { CMB } } , we obtain Local Group velocity in CMB frame : { V } _ { { LG } \rightarrow { CMB } } = ( -41 \pm 303 , -497 \pm 155 , 445 \pm 144 ) or 668 km s ^ { -1 } towards l = 265 and b = 42 .
This estimation is in good agreement , within 1 \sigma level , with the estimation of Yahil et al ( 1977 ) .