Gran Telescopio Canarias

First light

The GTC began its preliminary observations on 13 July 2007, using 12 segments of its primary mirror, made of Zerodur glass-ceramic by the German company Schott AG. Later, the number of segments was increased to a total of 36 hexagonal segments fully controlled by an active optics control system, working together as a reflective unit. Its first instrument was the Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS). Scientific observations began in May 2009.

Inauguration ceremony

The Gran Telescopio Canarias formally opened its shutters on July 24, 2009, inaugurated by King Juan Carlos I of Spain. More than 500 astronomers, government officials and journalists from Europe and the Americas attended the ceremony.

Instrumentation

GTC hosts a suite of advanced instruments, including:

• OSIRIS: Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy The IAC's OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy), is an imager and spectrograph covering wavelengths from 0.365 to 1.05 μm. It has a field of view (FOV) of 7 × 7 arcmin for direct imaging, and 8 arcmin × 5.2 arcmin for low resolution spectroscopy. For spectroscopy, it offers tunable filters.

• EMIR: Espectrógrafo Multiobjeto Infra-Rojo (near-infrared multi-object spectrograph)

• MEGARA: Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía is an optical integral-field and multi-object spectrograph covering the visible light and near infrared wavelength range between 0.365 and 1 μm with a spectral resolution in the range R=6000–20000. The MEGARA IFU (also called the Large Compact Bundle, or LCB) offers a contiguous field of view of 12.5 arcsec x 11.3 arcsec, while the multi-object spectroscopy mode allows 92 objects to be observed simultaneously in a field of view of 3.5 arcmin x 3.5 arcmin by means of an equal number of robotic positioners. Both the LCB and MOS modes make use of 100 μm-core optical fibers (1267 in total) that are attached to a set of microlens arrays (with 623 spaxels in the case of the LCB and 92 x 7 in the case of the MOS) with each microlens covering an hexagonal region of 0.62 arcsec in diameter.

• HiPERCAM: High-speed optical camera

• CanariCam: is designed as a diffraction-limited imager. It is optimized as an imager, and although it offered a range of other observing modes, these did not compromise the imaging capability. CanariCam worked in the thermal infrared between approximately 7.5 and 25 μm. At the short-wavelength end, the cut-off was determined by the atmosphere—specifically atmospheric seeing. At the long wavelength end, the cut-off was determined by the detector; this loses sensitivity beyond around 24 μm, although the cut-off for individual detectors varied significantly. CanariCam was a very compact design. It was designed for a total weight of the cryostat and its on-telescope electronics to be under 400 kg.^{[citation needed]} Most previous mid-infrared instruments have used liquid helium as a cryogen; one of the requirements of CanariCam was that it should require no expensive and difficult to handle cryogens.^{[citation needed]}. CanariCam used a two-stage closed cycle cryocooler system to cool the cold optics and cryostat interior to approximately 28 K (−245 °C; −409 °F), and the detector itself to around 8 K (−265 °C; −445 °F), the temperature at which the detector worked most efficiently. CanariCam was decommissioned as of February 2021^[update].