A CURVE OF GROWTH FOR ASTRONOMERS ON THE CITATION-INDEX

The average citation career of a sample of 72 astronomers who received their PhD between 1977 and 1988, and who were employed in astronomy i n 1994, is analysed using data from the Science Citation Index. The ci tation rates n(i)(t) are fairly well represented by the assumption n(i )(t) = alpha(i)f(t) where f(t) is a 'universal' function and alpha(i) an individual 'amplitude factor'. The shape of f shows shows that the citation rate two years after PhD is, on average, already one half of what it will be 12 years after PhD. Probability intervals are given fo r the later citation rate, for given rates early in the career. Early citation rates are found to have a modest but measurable predictive va lue.