H-I AND CO OBSERVATIONS OF THE CIRCUMNEBULAR ENVELOPES OF PLANETARY-NEBULAE

lambda=21 cm spectral-line and continuum observations of 10 compact planetary nebulae (PNe) have been made with the Very Large Array. Circumnebular atomic hydrogen is identified in the PNe SwSt 1, M 3-35, and possibly in Hu 2-1. The possibility of an inverse correlation between the optical depth of circumnebular atomic hydrogen and the linear radius of the ionized nebula is investigated, but shown not to be statistically significant. Observations of J=2-->1 CO emission for 22 PNe and J=3-->2 CO emission for 16 PNe taken with the James Clerk Maxwell Telescope are presented. J=2-->1 CO emission is detected in the planetary nebula M 1-59, and previous CO detections in IC 5117, M 1-16 and NGC 6302 are confirmed. J=3-->2 CO emission is detected in the PNe IC 5117 and NGC 6302.