The PIs will measure the excess brightness of the Sun in the CaII K-line, bringing up to date the sequence of measurements obtained at McMath-Hulbert from 1944-1979, and at Big Bear from 1979-1987. The CaII index is an important measure of the level of solar activity, solar ultraviolet emission, and excess solar constant emission. As such, it plays a basic role in the SunRISE program. The measurements in this project will separately evaluate the emission from highly active regions, normal plages, and the chromospheric network, all of which are known to be associated with sources of ultraviolet emission.***
