Telescopio Infrarosso del Gornergrat . The italian national telescope ( TIRGO ) was located on the northern tower of the Kulm Hotel at Gornergrat (3135 m altitude) near Zermatt . It was a 1.5m Cassegrain telescope with a wobbling secondary and optimized for infrared observations. Its operations terminated in spring 2005. ... with about 300.000 publicly available image . An introduction (in Italian) to infrared astronomy and TIRGO . ... Sky and Telescope Tirgo images . ...