Bilateral symmetry in the supernova remnant G 296.5+10.0

G296.5 + 10.0 is a barrel-shaped supernova remnant (SNR) with a remarkable degree of bilateral (reflection) symmetry. We have made a quantitative analysis of this symmetry with a view to understanding the origin and overall morphology of the radio structure. This analysis demonstrates that the small-scale filamentary features that are seen in the two halves of the remnant are highly correlated across the large-scale symmetry axis. We regard the presence of significantly correlated small-scale structures as evidence against models in which the bilateral symmetry of the remnant is imposed by the direction and strength of the local magnetic field prior to the formation of the remnant. Rather, a mechanism whereby the symmetry is caused by the ejection of material and magnetic fields from the progenitor star, the supernova, or the central compact neutron star is more likely to explain the overall morphology.