1 Introduction

FS Aur was discovered and first classified as a dwarf nova by Hoffmeister (1949). This little-studied system varies between aproximately $V=15\hbox{$.\!\!^{\rm m}$ }$4-16 $\hbox{$.\!\!^{\rm m}$ }$2 in quiescence and $V=14\hbox{$.\!\!^{\rm m}$ }4$ in outburst. Optical photometry during quiescence was reported by Howell & Szkody (1988) who found a modulation with period $P=97\pm10$ min, characteristic for SU Uma - type stars. The long term light curve was analysed by Andronov (1991). He found normal outbursts only with a probable interval between them of 12$^{\rm d}$ and no superoutburst. Therefore the SU Uma classification of this star is tentative.

Spectroscopic observations by Williams (1983) showed a typical dwarf nova spectrum with strong emission lines of hydrogen and HeI. H$\alpha$velocity variations with a period of $85.7\pm0.18$ min have been reported by Thorstensen et al. (1996; TPST hereafter). No other study of emission lines has been made for FS Aur. This motivated us to perform time-resolved spectroscopy and photometry of FS Aur in order to study its properties in more detail.