HST/STIS echelle spectra of the dM1e star AU Microscopii outside of flares

We report on observations of the dM1e flare star AU Microscopii obtained wi th the Space Telescope Imaging Spectrograph (STIS) on 1998 September 6. A t otal of 10,105 s of observations were obtained with the medium-resolution E 140M grating. We report here on the 9200 s of "quiescent" data when the sta r did not obviously flare. In this data set, we identify 142 emission lines from 28 species, including low-temperature chromospheric lines (e.g., C I, O I), transition-region lines (e.g., C II-IV, N IV, O III-V, Si II-IV), an d the coronal line Fe XXI 1354 Angstrom. There are a number of intersystem lines that are useful for measuring electron densities. We discuss line red shifts and the broad wings of transition-region lines that provide evidence of microflare heating. We derive the emission-measure distribution and com pare it with the solar one. We also discuss the shape and formation mechani sms of the He II 1640 Angstrom lines. The analysis of the flare data and of the interstellar absorption features seen in the H I, D I, C II, and O I r esonance lines will be published elsewhere.