1E 0643.0-1648

T. Chlebowski, J. P. Halpern and J. E. Steiner, Harvard-Smithsonian Center for Astrophysics, communicate: "We have discovered a new galactic x-ray source which is positively identified with a star 9' south of Sirius. The position is (equinox 1950.0) R.A. = 6h43m03s.5, Decl. = -16o48'25". Optical and x-ray properties clearly demonstrate that it is a cataclysmic variable, possibly of an AM Her-type. Examination of the Harvard archive plates shows low (V ~ 13.5) and high (V ~ 11) states. Optical monitoring with the 1.6-m telescope at the Brazilian Astrophysical Observatory and x-ray observations with the Einstein satellite both show flickering with timescales from 1 to 10 min. Einstein observations also indicate a hard spectrum (kT ~ 10 keV) with a flux of 3 x 10**-15 J m**-2 s**-1 keV**-1 at 3 keV when the source is at an x-ray high state. Optical spectra taken at Cerro Tololo Interamerican Observatory show Balmer lines, He I and variable He II in emission."