The International Outer Planet Watch is a program for the encouragement and coordination of the study of temporal variations in the Outer Planets. The IOPW coordinates 24-hour coverage of outer planet phenomena when such coverage is needed. It provides a mechanism for the rapid sharing of information to the community of scientists studying the outer planets. The measurements it fosters provide a long term context for "snapshots" that in situ spacecraft, like Galileo and Cassini, provide. The program is built on the belief that cooperation achieves more than the random efforts of the same number of investigators; that much can be accomplished in the ground-based program especially in concert with a major in situ investigation; and that long term observations of the outer planets are essential to understanding their behavior. This program was originally founded as the International Jupiter Watch (IJW) to complement the Galileo program. A brief history of the IJW can be found in Russell et al. (1990) and in the preface to NASA SP-494,Time Variable Phenomena in the Jovian System (1989) .
The IOPW is coordinated by volunteer discipline working group leaders who are listed below. Oversight is provided by a steering committee presently chaired by Glenn Orton
