Neon III in planetary nebulae.

We show that there is remarkably little variation in the Ne 11110 III abundance ratio among the bright planetary nebulae. This makes it reasonable to use the intensity ratio of the nebular transitions Ne iii A3869/ O iii A5007 to aid in estimating the electron density and temperature where suitable auroral to nebular intensity ratios are not available. Subject headings: abundances, nebular - planetary nebulae