spaceweb@oulu.fi - last update: 25 November 1998, 2200 UT . Diffuse aurora are found on the equatorward part of auroral oval , in the region of the so-called central plasma sheet (CPS) precipitation most likely mapping to inner plasma sheet , where magnetic field is almost dipolar (see isotropic boundary ). ... The strongest diffuse auroras are found on the post-midnight sector, i.e., they are produced mainly by electrons. ... First space observations were by Lui and Anger (1973). ... Space Sci., ...