RV Cass Spectrograph

The Radial Velocity Cassegrain Spectrograph (RV Cass Spectrograph) — also known as the Chilicass — was mounted at the f/15 focus of the ESO 1.52-metre telescope at the La Silla Observatory, Chile, in 1969. This spectrograph was borrowed from the Marseille Observatory (now the Haute-Provence Observatory).

In the early years of its use, most of the observing time with the RV Cass Spectrograph was devoted to defining the radial velocities and spectral types of the stars in the Magellanic Clouds, which were previously detected by the Grand Prisme Objectif telescope (GPO) observations in South Africa.

The RV Cass Spectrograph employed a 600 lines/mm Littrow mounted grating and had a curved focal plane. The optics were coated for maximum efficiency at 425 nm and the spectrograph could be used in the wavelength range between 340 and 550 nm. The spectrograph was also equipped with two viewfinders; a wide field (7 arcminutes) finder, and a small field (3 arcminutes) for guiding. Several filters could be used with the spectrograph, including two neutral density filters for observation of bright stars. The exposure time with good quality seeing (1 to 1.5 arcseconds) was 1 hour to reach magnitude 10 stars and 3 hours to reach magnitude 12.

Its most notable uses include observing the W UMa star YY Eri, in order to obtain the spectroscopic mass of its components by direct measurements of their radial velocities from intermediate dispersion spectra.

The RV Cass Spectrograph was decommissioned in the 1980s.

RV Cass Spectrograph

This table lists the global capabilities of the instrument.

Location: Decommissioned
Telescope: ESO 1.52-metre telescope
Focus: Cassegrain
Type: Spectrograph
Wavelength range: 340–550 nm
Spatial resolution: 9.2 arcseconds mm-1
Spectral resolution: 7.4 nm mm-1
First light: 1969
Science goal:
  • Measurement of radial velocities and spectral types of stars.
Images taken with the instrument: N/A
Images of the instrument: Link
Press Releases with the instrument: N/A
  • ESO
  • Haute-Provence Observatory