Nebular Spectrograph C

Year: 1972
Manufacturer: Officine C.O.M. – Florence
Materials: Aluminum, steel, brass, optical glass
Dimensions: L = 70 mm; P = 360 mm; H = 70 mm; Weight: 27.5 kg

Made in 1972 by the Officine C.O.M. in Florence, spectrograph C was designed for the Newtonian focus of the Galileo telescope and was particularly suitable for extragalactic studies.

The instrument includes a specular slit with variable aperture and a parabolic mirror collimator. It has two interchangeable Bausch & Lomb gratings, with dispersions of 120 Å/mm and 240 Å/mm, and a Schmidt-Cassegrain lens with an effective focal length of 147 mm, f/1.4. At its focus is an electrostatic intensifier tube with optical fibers, used with Kodak 103a-D photographic plates.

Thanks to its reduced dimensions (compared to spectrographs A and B), the instrument could be mounted or removed from the telescope quickly, even during the same observation night. The system is completed by two optional filters, GG 475, and BG 38, for the suppression of the second order spectrum or the infrared zone.

Spectrograph C represented a light and versatile evolution in astronomical instrumentation, ideal for precision observations in the extragalactic field.