Extragalactic Spectroscopy with SIRTF/IRS

The Infrared Spectrograph (IRS) is one of the three instruments on board the Space Infrared Telescope Facility (SIRTF) to be launched in December 2001. The IRS will provide high resolution spectra (R = 600) from 10-37 microns and low resolution spectra (R >= 60) from 5-40microns. Its high sensitivity and ``spectral mapping''-mode make it a powerful instrument for observing both faint point-like and extended sources. We discuss the performance of the IRS on faint extragalactic targets and present simulated spectra of starbursts and AGNs at high redshift. In addition, we discuss the determination of redshifts from the low resolution spectra.