National Radio Astronomy Observatory
Green Bank, West Virginia
Technical Discription: 140 Foot Radio Telescope
Reflector:
Paraboloid diameter: 140 feet. Surface: 1/8 inch aluminum plate. Surface
tolerance: 0.030 inches at zenith. Contains: 350 tons of aluminum, 35
tons of concrete ballast, 5 tons of balancing blocks.
Focus:
60 feet above the surface. Carries 1/2 tons of receiving equipment.
Position relative to paraboloid stable to 1/4 of an inch.
Declination Axis Shaft:
Length: 67-1/2 feet overall; 57 feet between bearings. Diameter: 2 feet.
Material: composite aluminum and steel shaft running in two spherical
roller bearings. Rotates 145degrees to -53degrees north of zenith and 92
degrees south.
Yoke:
Serves to support the declination shaft and to rotate the antenna east
and west about the polar axis by means of the polar gear.
Polar axis Shaft:
Length: 67 feet. Diameter: 12 feet. Weight: 555 tons of steel; 170 tons
of high density concrete ballast. Rotates 220degrees -110degrees east
of meridian and 110degrees west.
Gear Sectors:
Diameter of polar sector: 84 feet. Diameter of declination sector: 71
feet.
Spherical Bearing:
Diameter: 17-1/2 feet. Surface tolerance: 0.003 inches. Floats on oil film
0.005 inches thick.
Base:
Height: 60 feet; 41 feet 6 inches to observation deck. Contains: 5700 tons
of concrete and 140 tons of steel. Wall thickness: 3 feet. Houses control
room, hydraulic and electric equipment, transformer vault, and electronic
workshop.
Total Moving Weight:
About 2,500 tons.
Mount:
Equatorial - Two mutually perpendicular axes.
Pointing Precision:
10 arc seconds - about the diameter of a dime at 400 yards.
Research Program:
Studies of known element and molecular spectral lines. Continuim research
at other than line frequencies. Generally at wavelenghts between 2 and 40
cm. Very-long base interferometry (VLB) using the 140-foot and non-NRAO
telescopes.
Date of Completion:
Spring, 1965