PLANETARY-NEBULAE EXPANSION DISTANCES

We present two epochs of lambda6 cm VLA maps of the planetary nebulae NGC 7027 and BD + 30-3639 with subarsecond angular resolution. By taki ng advantage of the high dynamic range possible with the VLA as well a s the almost 6 yr time baseline between the two epochs, we have constr ucted difference maps that show the signature characteristic of the ra dial expansion of the ionization front surrounding the nebulae. We hav e combined these results with the Doppler expansion velocities to esti mate the distance to both objects. Our results indicate that D(NGC 702 7) = 703 +/- 95 pc and D(BD + 30) = 2680 +/- 810 pc.