The physical structure of the point-symmetric and quadrupolar planetary nebula NGC 6309 R. Vázquez, L. F. Miranda, L. Olguín, S. Ayala, J. M. Torrelles, M. E. Contreras and P. F. Guillén A&A, 481 1 (2008) 107-116 Published online: 04 February 2008 DOI: 10.1051/0004-6361:20078520