Coronal Variability in the Extreme Ultraviolet

Late-type stars are the most numerous among the many different categories of object detected in the first all-sky survey of the 60--760 Angstroms region recently completed by the Extreme Ultraviolet Explorer satellite (EUVE). To date, this survey has yielded extreme ultraviolet (EUV) photometric data for nearly 200 late-type stars. Two years earlier, photometry was obtained by the ROSAT Wide Field Camera (WFC) in the 60--200 Angstroms band. Using both data sets, we have looked for changes over this two year period in the coronal emission from the late-type stars that have been detected by both EUVE and the ROSAT WFC. The results are discussed with reference to stellar activity cycles and flaring. This work has been supported by NASA contract NAS5--30180.