feature is left until sects.5 and 7, however the  absorption provides an upper limit to the hydrogen column density along the line of sight to FOAqr.

A pure damping Lorentzian profile (Bohlin 1975) convolved with a 7Å FWHM Gaussian has then been fitted to the  absorption line (Fig. 1, bottom panel). The resulting neutral hydrogen column density is ${\mbox{$N_{\rm H}$}}=(5.0\pm1.5)\times 10^{20} \,
\rm cm^{-2}$. The residual from the fit shows an emission line with maximum flux at $\sim 1215$Å , probably geocoronal or intrinsic, with an excess of flux in the blue wing possibly due to emission of SiIII $\lambda$1206.

The derived value for is consistent with the total interstellar column density in the direction of FOAqr as derived from Dickey & Lockman (1990) and with the upper limit estimated from X-rays (Mukai et al. 1994). Assuming an average gas-to-dust ratio (Shull & van Steenberg 1985), this upper limit corresponds to a reddening of $\rm E_{B-V} \approx 0.1$. Although FOAqr was already known to be negligibly reddened from IUE observations (Chiappetti et al. 1989), an upper limit $\rm E_{B-V}=0.013 \pm$ 0.005 is derived from the absence of the 2200Å absorption in the FOS data. This indicates that, despite the coincidence, 