In the TeV blazars Mkn421 and Mkn501, the same electrons are thought to be responsible for the synchrotron X-rays and TeV Comptonized emission. As a prelude to simultaneous X-ray/TeV analysis, we present results from variability studies of Mkn 421 and Mkn 501. We find that each source has a variability of 5% r.m.s. amplitude on time scales shorter than 20 minutes. We find some evidence that the hard X-ray flux may be more variable than the soft X-ray flux in Mkn 421. For Mkn 501 we also present comparisons with nearly simultaneous TeV observations taken by the HEGRA collaboration.
- BL Lac objects: individual (Mkn 501, Mkn421)
- X-rays: observations