Deep optical observations of the interaction of the SS 433 microquasar jet with the W50 radio continuum shell

Four mosaics of deep, continuum-subtracted, CCD images have been obtained over the extensive Galactic radio continuum shell, W50, which surrounds the remarkable stellar system SS 433. Two of these mosaics in the ${\mathrm H_\alpha}+[\mathrm N_{II}]$ and [O iii] 5007 Å emission lines, respectively, cover a field of $\sim 2{\buildrel {\circ} \over{.}3}$ which contains all of W50 but at a low angular...