On the OiiGround Configuration Energy Levels

The most accurate way to measure the energy levels for the O II 2p^3 groundconfiguration has been from the forbidden lines in planetary nebulae. Wepresent an analysis of modern planetary nebula data that nicely constrain thesplitting within the ^2D term and the separation of this term from the ground^4S_{3/2} level. We extend this method to H II regions using high-resolutionspectroscopy of the Orion nebula, covering all six visible transitions withinthe ground configuration. These data confirm the splitting of the ^2D termwhile additionally constraining the splitting of the ^2P term. The energies ofthe ^2P and ^2D terms relative to the ground (^4S) term are constrained byrequiring that all six lines give the same radial velocity, consistent withindependent limits placed on the motion of the O+ gas and the planetary nebuladata.Comment: 20 pages, 3 figures. To be published in Ap