Simultaneous X-Ray and Optical Observations of AN Ursae Majoris during a Low State

X-ray observations throughout the orbital cycle of AN UMa during its low state were conducted with the Einstein Observatory simultaneously with ground-based optical UBV photometry and spectroscopy. The observed low X-ray flux of 7X 10-l3 ergs cm-2 s-I is a factor of 40 below the high-state X-ray flux, and FX/Fqt is about a factor of 50 lower than for AM Her and 2A 031 1-227. There is marginal evidence for an X-ray eclipse coincident with an optical minimum and for increased X-ray flux at magnetic phase 0.4 which does not correlate with any optical continuum variation but may be related to increased hydrogen and helium line emission fluxes. Subject headings: stars: individual X-rays: binaries