Context :

Aims : We analyse the point-symmetric planetary nebula NGC 6309 in terms of its three-dimensional structure and of internal variations of the physical conditions to deduce the physical processes involved in its formation .

Methods : We used VLA-D \lambda 3.6 -cm continuum , ground-based , and HST-archive imaging as well as long slit high- and low-dispersion spectroscopy .

Results : The low-dispersion spectra indicate a high excitation nebula , with low to medium variations of its internal physical conditions ( 10 , 600 { K } \lesssim T _ { e } [ O iii ] \lesssim 10 , 900 { K } ; 10 , 100 { K } \lesssim T _ { e } [ N ii ] \lesssim 11 , 800 { K } ; 1440 { cm } ^ { -3 } \lesssim N _ { e } [ S ii ] \lesssim 4000 { cm } ^ { -3 } ; 1700 { cm } ^ { -3 } \lesssim N _ { e } [ Cl iii ] \lesssim 2600 { cm } ^ { -3 } ; 1000 { cm } ^ { -3 } \lesssim N _ { e } [ Ar iv ] \lesssim 1700 { cm } ^ { -3 } ) .
The radio continuum emission indicates a mean electron density of \simeq 1900 cm ^ { -3 } , emission measure of 5.1 \times 10 ^ { 5 } pc cm ^ { -6 } , and an ionised mass M ( H ii ) \simeq 0.07 M _ { \odot } .
In the optical images , the point-symmetric knots show a lack of [ N ii ] emission as compared with similar features previously known in other PNe .
A rich internal structure of the central region is seen in the HST images , resembling a deformed torus .
Long slit high-dispersion spectra reveal a complex kinematics in the central region , with internal expansion velocities ranging from \simeq 20 to 30 km s ^ { -1 } .
In addition , the spectral line profiles from the external regions of NGC 6309 indicate expanding lobes ( \simeq 40 km s ^ { -1 } ) as those generally found in bipolar nebulae .
Finally , we have found evidence for the presence of a faint halo , possibly related to the envelope of the AGB-star progenitor .

Conclusions : Our data indicate that NGC 6309 is a quadrupolar nebula with two pairs of bipolar lobes whose axes are oriented PA= { 40 \degr } and PA= { 76 \degr } .
Equatorial and polar velocities for these two pairs of lobes are 29 and 86 km s ^ { -1 } for the bipolar system at PA= { 40 \degr } and 25 and 75 km s ^ { -1 } for the bipolar system at PA= { 76 \degr } .
There is also a central torus that is expanding at 25 km s ^ { -1 } .
Kinematical age for all these structures is around 3700 to 4000 yr. We conclude that NGC 6309 was formed by a set of well-collimated bipolar outflows ( jets ) , which were ejected in the initial stages of its formation as a planetary nebula .
These jets carved the bipolar lobes in the previous AGB wind and their remnants are now observed as the point-symmetric knots tracing the edges of the lobes .