PG 1416-129 - A BROAD ABSORPTION-LINE QSO WITH LOW INTRINSIC X-RAY-ABSORPTION

A ROSAT PSPC spectrum of the close broad absorption line (BAL) QSO PG 1416-129 is presented. The spectrum is very well fitted by a power law with spectral index alpha = 1.2+/-0.15. This is much steeper than the very flat spectrum (alpha = 0.1) found from earlier GINGA observation s. The change in spectral slope occurs around 3 keV. We derive an uppe r limit on the column density of the broad absorption line region of 2 x 10(21)cm(-2) if the absorbing matter is assumed to have an ionizati on parameter at which significant amounts of the observed CIV and NV i ons are present, and 10(20)cm(-2) if it is cold. This low upper limit, in combination with the large equivalent width of the BALs, constrain s the ionization parameter in the BAL clouds and indicates that these clouds can not be very optically thick in the UV resonance lines of NV and CIV.