The Cassegrain station of the Gran Telescopio Canarias (GTC)

Abstract

The Gran Telescopio Canarias (GTC) has been recently equipped with the Main Cassegrain Focal Station (CG-Set), composed of an Instrument Rotator (IR) and the corresponding Acquisition, Guiding and Wavefront Sensing (AGWS) system. A shutter protects the Science Instrument during maintenance operations. IDOM was awarded in November 2017 the supply of this equipment, covering its design, manufacturing, assembly and commissioning of the CG-Set. The equipment was transported to the Observatorio del Roque de los Muchachos (ORM) in December 2019. The Site Acceptance Tests were successfully completed in January 2020. The final installation on the telescope has been carried out at the end of November 2020. The Cassegrain Station features a compact and lightweight design with an innovative cable wrap solution. This design results in a smooth and precise movement, whilst guarantees good access to relevant components, simplifying the maintainability. The CG-Set permits a range of movement of the Instrument Rotator of ±270o, providing a tracking accuracy better than 7 arcsec. The AGWS Mechanics provides the required pointing and focusing capabilities, using a reference star to accurately correct the telescope drives and optics. The Cassegrain Focal Station is remotely commanded from the Telescope Control System (GCS) during normal operation and from the Local Control System (LCS) supplied by IDOM for maintenance. For this purpose, two mobile HMIs can be connected at different locations. The Local Interlock and Safety System (LISS) communicates with the Telescope Interlock and Safety System (ISS) to guarantee safe operation of the CG-Set on both local and remote operation. This system is accommodated in an active thermally controlled electronic cabinet The project has been financed by both Spanish and Canary Governments (European Regional Development Funds).