Fig* 1. The antenna system at Cambridge, just completed> which located the only four known pulsars. Electrical switching can sweep the beam lobe A S and E-W across the sky.

in our own galaxy hut the weight of the evidence indicates they are very far out and may be some of the most distant objects observable by both optical and radio means.

As the radio astronomers have built more effective radio telescopes they have continued to find interesting new facts, challenges, and problems, Radio astronomy has provided much useful information for cos-mologists thinking about the nature and age of our universe. Some quiet, steady and nearly undetectable radio noise that comes in equally from all directions appeal's to be the still-echoing whisper remaining from the furious thunder of creation an estimated 26 billion years ago. This observation has received some attention over several vears but il is not regarded as a very important matter.

While I was researching this article I ciime across a very interesting letter published bv one radio astronomer who thinks a recent radio survey may have seen halfway around the universe. Some extremely faint, distant radio objects observed in a certain direction just might be, he suggests, the same ones we discover by looking in the opposite direction. He supplied a list of five prime possibilities and another five less likely candidates. If this is correct then we have some very useful information for testing theoretical investigations into the age and size of the universe.


One requirement for the continued devel-opement of radio astronomy has been better antennas and receivers. Another has been improvements in methods of detecting weak signals, and some of this work has appeared in the amateur radio field in moonbounce and space communications work. In a remarkable boundary-jumping effect, one valuable radio astronomy result has been the development of improved methods for studying human brain function. This has some very important and useful medical applications.

It was a natural development in 1967 for Cambridge University, in England, to be building a new and better radio telescope. The new instrument s antenna consists of a 28 x 16 planar array of full-wave dipoles with tillable plane reflectors, The system's long axis extends in an east-west direction as shown in Fig, L

Tins system was designed to operate at about 81,5 MHz, Its beam direction is changed by switching in time delays from different sets of elements, so that without moving the antenna its lobe can be pointed at different parts of the sky, fhe antenna can be used with up to four receivers simultaneously to look in four different directions, a mass-production arrangement appropriate for achieving the maximum use from a rather expensive installation.

The new radio telescope was finally put into operation in July, 1967, Its operators started making regular routine sky surveys, a simple business of mapping the sky's radio brightness time and time again, looking for changes, and anything unusual, of interest. They observed some sporadic interference of unknown source and finally, in November of 1967, they started looking for the cause.

An answer appeared shortly. The appar


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