1 Introduction

The star HD93521 is a high galactic latitude O-star. It has been used for many years as a tracer of the interstellar gas in the galactic halo, for which it is well suited due to its brightness (V=7.04), high galactic latitude ( $l\,=\,183\hbox{$^\circ$ }$, $b\,=\,62\hbox{$^\circ$ }$) and large rotational velocity ( $v \sin i \approx 400$ kms^-1, Lennon et al. [1991]). Together with a z-distance of about 1.5kpc (Irvine [1989]), HD93521 is an ideal candidate for studying kinematics of the halo gas, since galactic rotation effects should be very small (Spitzer & Fitzpatrick [1992]).

With the Echelle spectrometer of the ORFEUS telescope (Orbiting and Retrievable Far and Extreme Ultraviolet Spectrometer) it was for the first time possible to observe all available absorption lines of interstellar molecular hydrogen towards HD93521. In the gathered spectra we identified 198 H₂-lines. These lines are very narrow and strong but unsaturated, which was the reason why many of them were used for wavelength calibration of the ORFEUS Echelle spectrometer. Also 67 other interstellar absorption lines and 14 lines of the Lyman series were identified. For completeness stellar and stellar wind absorption lines are shown too.

We present the whole Echelle spectrum of HD93521, obtained during the second ORFEUS-SPAS mission in November/December 1996. This spectrum has a good signal to noise ratio and the spectral resolution achieved is somewhat higher than the claimed resolution of $\lambda$/$\Delta$$\lambda$=10.000 (Barnstedt et al. [1999]).

The plots presented in the Appendix show one Echelle order per plot for wavelengths above 1130Å (Echelle orders 40 to 49), and half an Echelle order per plot for Echelle orders 50 to 61 ($\lambda$<1130Å) where all H₂-lines are included.