OPTICAL OBSERVATIONS OF PLANETARY-NEBULA CANDIDATES FROM THE NORTHERN-HEMISPHERE

We present H alpha+[N II] images of 17 and low resolution spectra of 1 4 IRAS-selected planetary nebula candidates. The H alpha+[N II] images are presented as finding charts. Contour plots are shown for the reso lved planetary nebulae. From these images accurate optical positions a nd mean optical angular diameters were determined. Optical spectra sho w that the IRAS-selected and radio detected planetary nebula candidate s are indeed planetary nebulae. Three planetary nebula candidates, pre viously not detected in the radio continuum were seen in H alpha. They are larger, low surface brightness planetary nebulae. Most of these I RAS planetary nebulae are heavily extinct, having an average A(V) of 7 magnitudes. About half of the planetary nebulae seem to be of low exc itation, having central stars with an effective temperature probably s imilar to 60.000 K or less.