Three dimensional imaging of aurora and airglow Björn Gustavsson Swedish Institute for Space Physics, Kiruna Abstract: This PhD thesis focuses on multi-station imaging of aurora and artificial airglow. The artificial airglow is caused by the EISCAT Heating facility in Ramfjordmoen Tromsø, and the aurora is caused by natural processes. The multi-station imaging makes it possible to determine the three dimensional distribution of the photon emission which enables a distinction to be made between the horizontal distribution and the altitude variation of emission. When this is done for several auroral emissions, it is possible to retrieve information about the precipitating electron spectra over a 200 by 200 km horizontal square. This gives a tool to monitor changes in energy spectra of the precipitating electrons and their impact on the ionosphere. The thesis presents an estimate of the three dimensional resolution of the Auroral Large Imaging System, and discusses the sensitivity of the resolution to noise and errors. It outlines a general stopping criteria and suggests an improvement. It presents an analysis of multi-station imaging which gives three dimensional distributions of the $O(^1D)$ 6300 Å emission with 10 second time resolution during HF pump modification. The three-dimensional distribution gives insight into ionospheric processes such as neutral gas diffusion and winds as well as giving constraints on the HF-pump wave ionosphere interaction. Keywords: Aurora, Artificial Airglow, Tomography.