Sunspot observations by Hisako Koyama: 1945โ1996
Sunspot observations by Hisako Koyama: 1945โ1996
ABSTRACT Sunspot records are the only observational tracer of solar activity that provides a fundamental, multicentury reference. Its homogeneity has been largely maintained with a succession of long-duration visual observers. In this article, we examine observations of one of the primary reference sunspot observers, Hisako Koyama. By consulting original archives โฆ