Tidal compression of the Local Supercluster

The effects of the extended low density region behind the Local Supercluster on various approaches to determining the motion of the Local Group are discussed. In particular it is shown that the method of comparing the local and global values of the Hubble constant could overestimate the infall velocity of the Local Group by 100 km s-1. These considerations are applied to the infall velocity determined from the Fornax and Grus clusters by previous authors. (author)