Performance evaluation of the Herschel/SPIRE imaging Fourier transform spectrometer

The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on ESA's Herschel Space Observatory. An imaging Fourier transform spectrometer, of the Mach-Zelmder configuration, provides low to medium resolution spectroscopic capability for SPIRE. The performance of the instrument is being evaluated during a series of test campaigns of the flight model before delivery to ESA. In this paper we present preliminary performance characteristics of the SPIRE spectrometer from the first test campaign of the flight model. We verify the instrument's conformance with fundamental design specifications such as spectral coverage and resolution. In addition, we identify, quantify, and explain some instrumental artefacts that have been observed during these tests.