THE UNUSUAL X-RAY AND OPTICAL-PROPERTIES OF THE ULTRASOFT ACTIVE GALACTIC NUCLEUS ZWICKY-159.034 (REJ1237+264)

Zwicky 159.034, one of the Seyfert galaxies identified with extreme-ul traviolet (EUV) sources detected during the ROSAT Wide Field Camera (W FC) all-sky survey, has unusual properties. The ROSAT Position Sensiti ve Proportional Counter (PSPC) 0.1-2.5 keV X-ray spectrum, obtained si multaneously with the WFC survey, appears extremely steep. Subsequent deeper pointed observations with ROSAT revealed that its 0.1-2.5 keV c ount rate had decreased by an extremely large amount (a factor of simi lar to 70). This is comparable to the variability amplitude seen in an other ultrasoft Seyfert, E1615 + 061. There appears to be similar to 1 0 times as much nux in the soft component as in any expected hard tail , suggesting that, in the absence of partial covering of the hard flux , the soft flux cannot arise via reprocessing of the hard tail. Zwicky 159.034's peculiar optical spectrum has permitted lines with widths s imilar to 1200-1500 km s(-1), and forbidden lines are weak or absent. Its optical spectrum shows evidence for variability, and might be used to study the role that reprocessed X-rays play in the formation of op tical lines.