Gran Telescopio Canarias and FACT Telescope against Milky Way

From lower left to the right side of the picture, we can see the silver dome of Gran Telescopio Canarias (GTC) with a 10,4 meters primary mirror reflecting telescope. It is designed to incorporate the most up-to-date technology and it is one of the most advanced telescopes in the world, actually, the largest one until now in the optical-infrared system. At right center, in the foreground, we can see the silhouette of the First G-APD Cherenkov Telescope (FACT), that is the first imaging atmospheric Cherenkov telescope using Geiger-mode avalanche photodiods (G-APDs) as photo sensors. The rather small, low-cost telescope will not only serve as a test bench for this technology in Cherenkov astronomy, but also monitor bright active galactic nuclei (AGN) in the TeV energy range. The First G-APD Cherenkov Telescope is assembled in Roque de Los Muchachos on the MAGIC site, mounted in the focus of one of the former HEGRA telescopes (CT3). In the background, the beautiful light coming from the central region of Milky Way is shining against the telescope structure, reflecting on its mirror surface. Behind the GTC dome, the sky is shining as a smooth band of an orange airglow, normally from oxygen atoms at 150-300km high where the atmosphere is so sparse and collisions so infrequent that the atoms have time to radiate ‘forbidden’ light.

|  Canon 60Da – ISO2500; 24mm at f/2; Exp. 15 secs. in 30/09/2013 at: 22h57 AM