Astronomy and Astrophysics Rosat Hri Observations of Seven High Redshift Quasars

We present ROSAT HRI observations of six quasars with redshifts > We include the observation of the radio-quiet quasar BG 57 9, whose redshift has recently been revised to z = 0.965. S4 0620+389, B1422+231, PKS 2215+02 and BG 57 9 are detected in the ROSAT energy band (0.1-2.4 keV). 2σ upper limits are given for the remaining objects. All X-ray sources are point like to the limit of the HRI point spread function. We report marginal evidence for X-ray variability in S4 0620+389 on timescales of several hours (rest frame). No significant X-ray variability is found in the gravitationally lensed quasar B1422+231 on rest frame timescales of hours and months. We present the spectral energy distributions for six of the high red-shift quasars and compare them to the mean distribution of low redshift quasars.