Improved spectroscopic measurements have been made on the NO(a (4) Pi(i)-X (2) Pi(r)) 11-O band, and new measurements on the 14-O band, bringing the explored region of the a (4) Pi state to within 0.3 eV of the NO dissociation limit. Doubling and mixing of dye laser radiation is used to access the 200-210 nm region with an ultraviolet linewidth of 0.15 cm(-1). The a (4) Pi molecules collisionally convert their energy to the B (2) Pi state, from which radiation is detected. Almost 300 lines have been observed in each of the two bands, and accurate spectroscopic constants are presented. New information is provided on the relative positioning of perturbed levels in the a (4) Pi and B (2) Pi states.