Galaxy kinematics from counter-dispersed imaging

Abstract

Determining the internal kinematics of a galaxy from planetary nebulae (PN) is usually a two step process in which the candidate PN are first identified in a target galaxy and then, in a follow up run, spectra are obtained. We have implemented a new technique in which two dispersed images at the wavelength of the [OIII] emission line at 5007A are combined to yield positions, magnitudes and velocities of the PN population in a single step. A reduction in observing time of about a factor 2 is attainable. We present here the proof-of-principle results.