THE COST-EFFECTIVENESS OF OBSERVATIONAL ASTRONOMICAL FACILITIES SINCE1958 .1. EFFECTIVENESS

How cost-effective are astronomical observational facilities in suppor ting leading-edge research? This paper is the first of two which analy se the ground- and space-based facilities used to produce the 15 per c ent most cited papers in the Astrophysical Journal (ApJ) and the Month ly Notices of the Royal Astronomical Society (MNRAS) in the first half of every fourth year from 1958 to 1994 inclusive, the number of such highly-cited papers being taken as a measure of the effectiveness of t he facilities. The analysis shows a gradual trend away from the use of small and medium-sized telescopes, such that two-thirds of all import ant, ground based, optical results were produced in 1994 with telescop es in excess of 2.54-m diameter. The 5-m Hale has been the most effect ive telescope when considered over the whole period 1958-1994 and is s till producing high-quality results, but the Anglo-Australian Telescop e has matched it in the second half of the period. The Einstein Observ atory Spacecraft and IUE led the spacecraft over the period as a whole , although the Compton Observatory, ROSAT and the Hubble Space Telesco pe have produced high-quality results near the end of this period. A s econd paper will examine whether these large, front-line facilities pr oduce as many good results per dollar as the smaller, less well-known ones.