Alan Serrano

Optical Identification of X-ray Sources in a High X-ray Flux Sensitivity area from the Rass

We have optically identified a complete sub-sample of ROSAT All-Sky Survey (RASS) X-ray sources contained in 6 study areas. Of the original 12°12° area near the NEP only one quarter was observed until now in order to keep the number of sources on a manageable size. This area is of particular interest because the RASS integration time is about a factor of ten longer than in the other areas and therefore a factor of 3– in flux. We have started to observe the RASS sources in the remaining 3/4 of this area. First results are presented.

Identification of a Complete Sample of Northern Rosat All-Sky Survey X-Ray Sources

In order to derive statistical properties of a com- plete X-ray selected sample of AGN we used the classification spectra of the RASS Selected Areas-North survey to study the luminosities, redshifts, X-ray/visual flux ratios, line widths, and various correlations between observed parameters of all Seyfert galaxies and QSOs in this sample. On the basis of these data we discuss implications for the current AGN models.

The new ultrashort-period cataclysmic variable RX J0757.0+6306

A new cataclysmic variable is identified as the optical counterpart of the X-ray source RX J0757.0+6306. The emission lines bear evidence of a strong disc with an S-wave with period of 75±1.4 min, which we identify with the orbital period of the system. CCD photometry reveals an additional period of 8.45 min. which is stable over five nights. We assume it is the spin period of the accreting primary. We tentatively identify RX J0757.0+6306 as an intermediate polar.