A Ritchey–Chrétien telescope (RCT or simply RC) is a specialized variant of the Cassegrain telescope that has a hyperbolic primary mirror and a hyperbolic secondary mirror designed to eliminate off-axis optical errors (coma). The RCT has a wider field of view free of optical errors compared to a more traditional reflecting telescope configuration. Since the mid 20th century, a majority of large professional research telescopes have been Ritchey–Chrétien configurations; some well-known examples are the Hubble Space Telescope, the Keck telescopes and the ESO Very Large Telescope.
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Ritchey–Chrétien telescope in the context of SPECULOOS
SPECULOOS (Search for habitable Planets EClipsing ULtra-cOOl Stars) is a project consisting of SPECULOOS Southern Observatory (SSO) at the Paranal Observatory in Chile and SPECULOOS Northern Observatory (SNO) at the Teide Observatory in Tenerife.
The SSO consists of four Ritchey–Chrétien telescopes of 1-metre primary aperture, made by ASTELCO. Each telescope is equipped with a NTM-1000 robotic mount and will search for Earth-sized exoplanets around 1000 ultra-cool stars and brown dwarfs. As of June 2019, the SNO consists of one telescope, but more might be added in the future with up to three telescopes for SNO. SPECULOOS is complemented by SAINT-EX and TRAPPIST.
View the full Wikipedia page for SPECULOOSRitchey–Chrétien telescope in the context of New Technology Telescope
The New Technology Telescope or NTT is a 3.58-metre Ritchey–Chrétien telescope operated by the European Southern Observatory. It began operations in 1989. It is located in Chile at the La Silla Observatory and was an early pioneer in the use of active optics. The telescope and its enclosure were built to a revolutionary design for optimal image quality.
View the full Wikipedia page for New Technology TelescopeRitchey–Chrétien telescope in the context of Synoptic Optical Long-term Investigations of the Sun
Synoptic Optical Long-term Investigations of the Sun (SOLIS) is a synoptic facility for solar observations over a long time frame that is funded by the National Science Foundation (NSF) and designed and built by the National Solar Observatory (NSO).It is operated by the NSO Integrated Synoptic Program (NISP).SOLIS is a single set of three instruments mounted on a common observing platform. The instruments are the 50 cm aperture Vector Spectromagnetograph (VSM), the 8 mm aperture Integrated Sunlight Spectrometer (ISS), and the 14 cm aperture Full-Disk Patrol (FDP). The VSM telescope is a quasi-Ritchey-Chretien design with a primary mirror operating at f/1.6. The ~ 400 W of solar light from the primary is reflected by a secondary mirror fabricated from a single silicon crystal. The final f/6.6 full-disk solar image is focused on a spectrograph slit that is cooled by a flow of chilled water-propylene glycol solution. The mirrors are coated with protected silver. To improve the internal seeing, the VSM is sealed by 74 cm diameter, 6 mm thick fused silica window. Originally, it was filled with helium at about ambient pressure and temperature. In 2014, helium was replaced by nitrogen due to the increasing cost of helium. Due to this change, the image sharpness was slightly degraded.
The VSM provides full-disk vector (strength and direction) maps of the solar magnetic field both in the photosphere and in the chromosphere on a daily basis, continuing the 40-year record of NSO magnetic field observations. The ISS obtains spectra of the Sun integrated over the solar disk, so the Sun appears as it would as a much more distant star. The combination of data from the ISS and the VSM is useful for studies of exoplanet systems as it allows the modeling of the influence of a star's magnetic field on its spectrum giving clues to the activity level that the exoplanets may be subject to. The FDP provides full-disk images of the Sun in a variety of spectral lines with a cadence as high as 10 seconds.
View the full Wikipedia page for Synoptic Optical Long-term Investigations of the Sun