Surprise in the

What are pukars? Radio astronomers and other scientists all over the world are trying to work out the unexpected mysten posed by four sets of strangely regular, short, sharply pulsed radio signals from space. Several months of effort have resulted in an impressive number of contributions to the scientific literature, but the possible sources suggested so far have not success-hilly accounted for tfie signals actually observed. At this writing (July 3, 1968) it appears nobody knows what pulsars are, and new measurements, just published, will probably obsolete much careful thinking. Hardly tongue-in-cheek, ■ suggest posers3' might be a better title for the sources of these remarkable signals from space.

Although pulsar signals are very powerful at their' point of origin> their distance of many tens or a few hundreds of lightyears attenuates the signals so that a good receiving system is needed to hear them. F. S+ Harris (Is that Sam Harris?) has heard them at Aricebo Observatory in Puerto Rico using a 50-foot paraboloidal reflector on 144 MHz, From this ii appears any ham who can try moonbounce work might be able to hear pulsars. This raises an interesting thought.

Why couldn't pulsars have been discovered by an amateur operator? Too bad they weren't. It would have done a lot for ham radio. Well, to find out something about pulsars lets start with a few notes on radio astronomy.

Radio astronomy

Radio astronomy originated before WW2 as an amateur electronics hobby rather than an amateur radio hobby. Rut it did not become a recognized scientific field until after WW2, when scientists using the radar and radio techniques developed for military applications, began to point their antennas out toward space to find out what they could hear.

It turned out they could hear a lot, and soon they were busy mapping the sky for radio brightness. Investigations in this field began to answer questions about our suns location in space, and provided information

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about the shape of our galaxy and the distance to its center. Radio astronomy complemented optical astronomy very well since radio signals could penetrate the huge dust clouds found in many parts of the sky and particularly toward the galactic center.

Just its the optical telescope is one of the prime tools of the optical astronomer, the radio astronomer works with a radio telescope. But a radio telescope is simply a very large radio antenna with strongly directional characteristics, rather than an array of lenses and mirrors. A very good radio receiver completes the research installation, which may be very simple,

I was surprised to discover there are a number of amateur radio astronomers in England. I haven't come across any mention of American amateur radio astronomers, but I think this special form of engineering electronics might be interesting to hams who would like to try some new ideas.

As the radio astronomy field developed it became important in its own right, Workers found many surprises including radio stars which could be observed by radio but were invisible to any optical system. Some other stars were found which were visible both by radio and light observation, and one of these is the very interesting Crab Nebula, a remarkable sight centered on a star believed to have exploded into a superil ova in our vear 1054 AD. Other radio obser-v at ions were made at various distances ranging from the planet Jupiter, right in our own backyard as such things go, out to several times the range of the visible universe.

Later, astronomers discovered the enigmatic sources called quasars, whose nature and distances are still uncertain. Opinions as to the nature of quasars have ranged from primitive galaxies in a very early stage of development to a radical suggestion they might he huge spaceships traveling in our own galaxy at relativistic speeds. Some observed facts suggest quasars are right here


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