EIT, the extreme-ultraviolet imaging telescope on board SOHO: First results.

EIT is a EUV telescope on board SOHO providing wide-field images of the corona and of the transition region, on the solar disc and up to 0.5 R-o above the limb. The multi-coated optics of the telescope select four emission lines to provide temperature diagnostics in a wide range, corresponding to the coronal plasma and the underlying cooler layer. This paper briefly presents the instrument and its first observations.