urn:nasa:pds:context:telescope:orm.gtc10m4 1.0 1.15.0.0 Product_Context 2021-07-23 1.0 Initial export from OLAF urn:nasa:pds:context:instrument:orm.gtc10m4.osiris telescope_to_instrument urn:nasa:pds:context:facility:observatory.orm telescope_to_facility 10.4 342.1081 28.7567 2267 Unknown The Gran Telescopio CANARIAS (GTC), is currently the largest and one of the most advanced optical and infra-red telescopes in the world. Its primary mirror consists of 36 individual hexagonal segments that together act as a single mirror. The light collecting mirror surface area of GTC is equivalent to that of a telescope with a 10.4m diameter single monolithic mirror. Thanks to its huge collecting area and advanced engineering the GTC classes amongst the best performing telescopes for astronomical research. The GTC has also a secondary mirror and a tertiary mirror that together with the primary mirror produce the telescope focal plane in the focal station of choice. The scientific instruments that are placed in the focal station then analyse and detect the light, and store the final data. The telescope mount, a large mechanical, steel structure that holds the mirrors, allows rotational movements of the telescope along a horizontal and vertical axis. This movement has to be extremely precise in order to keep the stars projected stably onto the detector. The telescope is designed so that it is able to observe the optical and infrared light ranges. GTC will be the last of the generation of so called 8 to 10 meter-class telescopes. Therefore it has tried to improved the design of the predecessors, learning from their experiences. GTC is the largest telescope thanks to its huge light collecting surface of 75.7 square meters (73 m2 effective area). Apart from its large collecting surface another key feature is the exquisite image quality that the telescope delivers and therefore it can exploit the good sky quality to its maximum. The good image quality is made possible thanks to the active adjustment of the optics. This active optics allows the alignment, deformation and movement the individual segments that form the primary mirror, as well as the alignment of the secondary mirror so as to always keep their optimal position independently of the external conditions (climate, temperature, gravity, manufacture faults, etc).