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‘Electronic and Computer-aided Astronomy: From Eyes to Electronic Sensors’
by Ian S. McLean, Ellis Horwood/Wiley, pp 297, 35 pounds

VERY FEW areas of life today – from taking a plane to washing your clothes
– are untouched by the silicon chip. Astronomers are particularly affected.
As well as relying on solid-state electronics and computers to control their
equipment and analyse their data, they use a particular type of silicon
chip to detect directly the faintest trickles of light from the night sky.

First invented in 1969, these ‘charge-coupled devices’, or CCDs, have
revolutionised astronomy. While a photographic plate can record only 2 or
3 per cent of the photons falling on it, a CCD can pick up about 80 per
cent, so slashing exposure times from hours to minutes. By linking the electronic
output into a suitable graphics display, astronomers can also dig out all
the information in the image much more easily than they can from a photograph.

Ian McLean, of the Royal Observatory in Edinburgh, has now produced
a comprehensive guide to the way that astronomers use CCDs. (Beware the
title, however: McLean’s book is about CCDs, not about the general use of
electronics and computers in astronomy.) Complete with a colour section
of CCD images, the book details everything from the history of CCDs – they
were invented for use in videophones – to the CCDs about to be launched
in the Hubble Space Telescope. As well as the theory of what CCDs are and
how they work, there’s plenty of practical detail about the way astronomers
use CCDs in the observatory and analyse the results at the computer console.

Putting these devices in the correct perspective for today’s optical
astronomers, McLean quotes Jasper Wall. He is in charge of the world’s leading
telescope devoted to probing the most distant parts of the Universe. Of
CCDs, he says: ‘About 90 per cent of everything done with the 4.2 metre
William Herschel Telescope to date is from CCDs. We live and breathe them
. . .’