Herschel-SPIRE: design, ground test results, and predicted performance.

SPIRE, the Spectral and Photometric Imaging Receiver, is a submillimetre camera and spectrometer for Herschel. It comprises a three-band camera operating at 250, 350 and 500 µm, and an imaging Fourier Transform Spectrometer covering 194-672 µm. The photometer field of view is 4×8 arcmin., viewed simultaneously in the three bands. The FTS has an approximately circular field of view of 2.6 arcmin. diameter and spectral resolution adjustable between 0.04 and 2 cm¿1 (¿/¿¿. =20-1000 at 250 µm). Following successful testing in a dedicated facility designed to simulate the in-flight operational conditions, SPIRE has been integrated in the Herschel spacecraft and is now undergoing system-level testing prior to launch. The main design features of SPIRE are reviewed, the key results of instrument testing are outlined, and a summary of the predicted in-flight performance is given.