The microchip revolution has made mathematical positional astronomy easy. Computing power, such as would have been the envy of even the most prestigious institutions several decades ago, is now commonplace in the home. Amateur astronomers can perform complex calculations with comparative ease, making predictions of forthcoming celestial events or demonstrating what took place in the past, with a precision that is almost unlimited.

Many books have already been published which list the steps (more or less clearly) to be followed to the desired answer.Some are for calculators, but others exploit the special powers of the microcomputer. Unfortunately, those in the former category do not provide programs which can be used immediately on the computer, while those in the latter category are often too specifically biased towards particular makes of machine and particular calculations. While it is always possible tomodify a program to work on another model or to make a different calculation, it is not always easy to do so, especially when detailed notes about its workings are not supplied.

This book is designed for the person who wishes to use his or her personal computer to make astronomical calculations with the minimum of fuss. It is not specific to any make of machine, neither are you confined to specific calculations. Rather, you are presented with a set of linking subroutines, each carrying out a specific task, which you can combine to form a complex program designed to your own requirements. You need only have a broad understanding of the problem; the subroutines themselves take care of the details.