Nature 372, 77 - 79 (03 November 2002); doi:10.1038/372077a0

Discovery of a nearby spiral galaxy behind the Milky Way

R. C. Kraan-Korteweg^*, A. J. Loan^†, W. B. Burton^‡, O.  Lahav^†, H. C. Ferguson^§, P. A. Henning & D.  Lynden-Bell^†

^*Kapteyn Astronomical Institute, Postbus 800, 9700 AV Groningen, The Netherlands
^†Institute of Astronomy, Madingley Road, Cambridge CBS OHA, UK
^‡Leiden Observatory, Postbus 9513, NL-2300 RA Leiden, The Netherlands
^§Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, Maryland 21218, USA
Department of Physics and Astronomy, University of New Mexico, 800 Yale Boulevard NE, Albuquerque, New Mexico 87131, USA

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 the emission differs from that of the local gas³. The new 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.

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