X-ray spectroscopy of the BL Lac PKS 0548-32

GT We propose to measure the parameters of the absorption feature at virgul600 eVoriginally detected by the Einstein SSS in PKS 054832. Sharp absorptionfeatures appear to be common in the soft Xray spectra of BL Lac objects, asshown by several detections made with BBXRT: the lines are generally attributedto blueshifted Lyman alpha OVIII resonance absorption, implying rapid massoutflow from the active nucleus. However, the exact nature and origin of thesefeatures is still unclear. The RGS will provide an accurate measure of the lineenergy and width, of the column density and the ionisation level of the gas,ultimately giving clues to the origin of the gas itself. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]