A comparison between theoretical and solar Fe XII UV line intensity ratios

A new set of radiative and electron collisional data for Fe XII was present ed in two earlier papers. In the present work, rye derive level populations and theoretical line intensities for a range of plasma densities and tempe ratures. Observations of Fe XII lines obtained with the Solar EUV Rocket Te lescope and Spectrograph are analysed both as a check the quality of the ne w atomic data and to determine the electron density in active regions and t he quiet Sun. The discrepancy between the electron density values determine d from Fe XII line intensity ratios and those obtained from other ions is i nvestigated.