[1] Koninklijke Sterrenwacht Belgie, B-1180 Brussels, Belgium
[2] Katholieke Univ Leuven, Inst Astron, B-3001 Louvain, Belgium
[3] UCL, Dept Phys & Astron, London WC1E 6BT, England
[4] Univ Vienna, Dept Astron, A-1180 Vienna, Austria
[5] European Space Astron Ctr, Herschel Sci Ctr, Madrid 28080, Spain
[6] CSIC, Dept Astrophys, CAB, INTA, Madrid, Spain
[7] Max Planck Inst Astron, D-69117 Heidelberg, Germany
[8] Univ Calif Berkeley, Radio Astron Lab, Berkeley, CA 94720 USA
[9] Univ Amsterdam, Sterrenkundig Inst Anton Pannekoek, NL-1098 Amsterdam, Netherlands
[10] Cardiff Univ, Sch Phys & Astron, Cardiff CF24 3YB, S Glam, Wales
[11] Royal Observ Edinburgh, UK Astron Technol Ctr, Edinburgh EH9 3HJ, Midlothian, Scotland
[12] Rutherford Appleton Lab, Space Sci & Technol Dept, Didcot OX11 0QX, Oxon, England
[13] Stockholm Univ, Dept Astron, AlbaNova Univ Ctr, S-10691 Stockholm, Sweden
[14] Univ Denver, Dept Phys & Astron, Denver, CO 80208 USA
[15] Inst Astrophys & Geophys, B-4000 Liege 1, Belgium
[16] Univ Libre Bruxelles, Inst Astron & Astrophys, B-1050 Brussels, Belgium
[17] Univ Lethbridge, Inst Space Imaging Sci, Lethbridge, AB T1J 1B1, Canada
[18] Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England
[19] Graz Univ Technol, Inst Comp Graph & Vis, A-8010 Graz, Austria