NEWS  RELEASE

Commonwealth Scientific and Industrial Research Organization Limestone Avenue Campbell A.C.T. RO. Box 225 Dickson A.C.T. 2602 Â· Tel. 48 4484 (Media Office) 47 8996 (After hrs) Cables Raocanb,Canberra Telex 62528  PR No. 1

INTERNATIONAL RADIOTELESCOPE ÃÂ³ Â· 7J

TO LINK-UP '

Radiotelescopes in Australia, the Soviet Union and the United States will link up this month in a

highly sophisticated experiment aimed at gathering clues about the birth of stars.

This was announced today by the Minister for Science, Senator J.J. Webster.

“The aim of the experiment is to measure accurately the size of water vapour ‘masers’

deep in space,’’ he said.

“Water vapour masers are clouds of energised water molecules which scientists believe may

represent an early stage in the birth of new stars. They are found in clouds of interstellar molecules

which are so dense and cold that they are collapsing rapidly under the force of their own gravity

to form fresh generations of stars and new planets. '

“The water vapour masers amplify microwave signals which can be picked up by

radiotelescopes.

“This first simultaneous experiment between radiotelescopes in three countries is being

conducted between 28 April and 6 May.

“The collaboration between Australian and Soviet scientists is under the Australia-USSR

Agreement on Scientific and Technical Co-operation.”

Senator Webster said that radiotelescopes at Tidbinbilla in the Australian Capital Territory,

Simeiz in the Crimea, Owens Valley, California, and at Maryland Point, Virginia, USA are to take part.

“A critical part of the experiment is to establish exact time synchronization (to a millionth

of a second) between atomic clocks in the Australian Capital Territory, in the Crimea, and in the USA.

“ Between the Crimea and Australia the time synchronization will be achieved by flying a

portable rubidium atomic clock, set in Moscow, from the USSR to Australia,” Senator Webster said.

“The telescope at Tidbinbilla is operated by NASA as part of its deep space network and is

made available to CSIRO from time to time for scientific investigations,” he said.

“CSIRO scientists will be working with Soviet and US scientists during the experiment.

“Prime target of this month’s experiment is a region of very active star formation at a

distance of 40,000 light years from Earth,” he added.

. . . 2/

2 .

Background The method to be used in the experiment is known as very long baseline interferometry (VLBI), It

uses radio interference produced from radiotelescopes directed at the same source at a given time

to measure the diameter of the source.

Atomic clocks at all four telescopes will synchronize the ‘tuning in’ of the telescopes to

an accuracy of a millionth of a second.

The masers are believed to be about the size of our own solar system, and cannot be

measured accurately unless the probing telescopes are as far apart as possible within the Earth’s

limits. The angular sizes of the objects to be measured are equivalent to picking out a football

at the distance of the moon.

Very long baseline interferometry (VLBI) requires no direct link between the four telescopes,

separated as they are by many thousands of kilometres. Instead, the raw data together with

synchronizing pulses from atomic clocks, is recorded directly on video tape at each telescope. The

four sets of video tapes will later be sent to the National Radio Astronomy Observatory, Virginia, USA

to be played back on a special processor, the only one of its kind in the world. During the playback

the tapes must be synchronized to one millionth of a second. Scientists will then search for

interference patterns between the radio signals stored on tape at the four separate telescopes many

weeks before.

The CSIRO Division of Radiophysics has fitted a special 13-millimetre wavelength receiver

to the NASA 64-metre radiotelescope at Tidbinbilla, as well as the highly sophisticated electronics

for synchronizing the signals. Results of the experiment are expected to be available for scientific

evaluation in Moscow after processing in the USA about mid-year.

Editor’s note: For details of Soviet scientists’ arrival at Mascot with the atomic clock, contactÂ·.

Bob Cousens,

Press Relations Manager,

QANTAS,

(02) 230 0699

Further information:

Wendy Parsons, '

CSIRO Media Office,

(062) 48 4479

A/H 54 1382

20 April 1976

