most of the neutral absorption is unrelated to the interstellar dust and hence it is likely located within the binary system.

Time series analysis
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The presence of periodicities in FOAqr has been investigated in the FOS continua, emission lines and zero-order light as well as in the optical photometric data.

HST UV data
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Fluxes in five line-free continuum bands have been measured in each FOS spectrum in the ranges $\lambda$1265–1275, $\lambda$1425–1450, $\lambda$1675–1710, $\lambda$2020–2100, $\lambda$2410–2500. Line fluxes of HeII $\lambda$1640, NV, SiIV and CIV and have been computed adopting a method which uses for the continuum a power law distribution as found from a fit in the above continuum bands. Furthermore, since the low spectral resolution of FOS data prevents the study of UV line profiles, measures of the V/R ratios of emission lines have been used to investigate possible motions in the lines. These are defined as the ratios between the integrated fluxes in the violet and red portions of the emission lines assuming as centroid wavelength that measured in the average profile. Such analysis is restricted to the strong emissions of HeII, CIV and NV lines whose FWZI are $\pm$3000, $\pm$4000and $\pm$3000respectively.

In order to detect the 