DISCOVERY OF A NEARBY SPIRAL GALAXY BEHIND THE MILKY-WAY

THE disk of the Milky Way contains a lot of gas and dust, which obscures about 20% of the extragalactic sky. Galaxies hidden behind the Milky Way may have an important influence on the dynamics of the Local Group and its peculiar motion relative to the cosmic microwave background radiation(1,2). Here we report the discovery of a large spiral galaxy, which we call Dwingeloo 1, during the course of a search for emission from atomic hydrogen (H I) associated with galaxies hidden by the disk of the Milky Way-such H I emission is not obscured by the disk if the velocity of tbe emission differs from that of the local gas(3). The nea galaxy seems to be associated with the group containing IC342 and the Maffei galaxies, and a subsequent optical image suggests that it is of type SBb. The detection of Dwingeloo 1 early in the course of this survey suggests that many more galaxies hidden behind the Milky Way remain to be discovered.