Astronomers and librarians have been experiencing difficulties in keeping up with the amount of published literature. The astronomer tries to keep abreast in his particular field and the librarian in the management, control and retrieval of scientific information. The 1980’s have seen a revolution in the methods for information storage and retrieval and in particular the advent of the online database. The speed of processing information for storage has been embraced by all, however little thought has been given to how we shall achieve effective high precision recall of documents.

Many librarians firmly believe the best road to success in information retrieval from automated systems is provided by vocabulary control. Contrary to belief, free text or natural language searching alone does not lead to high precision recall. Consistency and integrity of the online catalogue can only be achieved with the addition of a controlled vocabulary. With today’s technology it is possible to maintain the best of both worlds. The controlled vocabulary is used to index the major concepts of a given document over and above the natural language used within the document.