Telescopes

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Interstellar atoms and molecules

Pulsars, quasars, radio galaxies

Cosmic microwave background

Slide 49

Carl Jansky’s telescope

Jansky's vertically polarized beam antenna was built in 1931 to study the direction of thunderstorms, which were suspected to cause signal-to-noise problems in Bell Lab’s initial transoceanic radio-telephone circuits.

In addition to detecting lightning, Jansky detected a signal that that appeared 4 minutes earlier each day and was strongest when Sagittarius was high in the sky.

The center of the Galaxy is in the direction of Sagittarius, so Jansky concluded that he was detecting radio waves from an astronomical source

Slide 50

Grote Reber’s telescope

Grote Reber read about Jansky's discovery.

In 1937, Reber built his own 32-foot-diameter parabolic dish antenna in his backyard in Wheaton, Illinois to seek cosmic radio emissions.

Slide 51

Grote Reber’s telescope

In the spring of 1939, he was able to detect cosmic radio emissions with his equipment. In 1941, he made the first survey of the sky at radio wavelengths (160MHz).

Slide 52

Reber’s telescope

On display at Greenbank Radio Observatory

Greenbank, WV

Slide 53

Radio, millimeter, and submillimeter astronomy

The place of radio, millimeter, and submillimeter astronomy the study of astronomy

The parts of a radio telescope and how it works

The two big challenges of radio astronomy overcome by radio astronomers

Tiny signal strength of radio signals

Low angular resolution

Next generation radio, millimeter, and submillimeter telescopes

Slide 54

Parts of a radio telescope

Antenna

Collects the radiation

Focuses the radiation on the receiver horn

Receiver

Horn

Amplifies the signal

Converts the radio-frequency signal to signals (current/voltage) we can record and analyze

Steering gear

Moves the telescope as it tracks the observed object

Slide 55

Parts of a radio telescope

Antenna

Receiver

Antenna

Receiver

Steering gear

Parkes 64-meter radio telescope

Slide 56

Film clip of Parkes Radio Telescope

from

“The Dish”

Slide 57