The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

摘要

The Photodetector Array Camera and Spectrometer (PACS) is one of the threescience instruments on ESA's far infrared and submillimetre observatory. Itemploys two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64pixels, respectively, to perform integral-field spectroscopy and imagingphotometry in the 60-210\mu\ m wavelength regime. In photometry mode, itsimultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m,over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling ineach band. In spectroscopy mode, it images a field of 47"x47", resolved into5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectralresolution of ~175km/s. We summarise the design of the instrument, describeobserving modes, calibration, and data analysis methods, and present ourcurrent assessment of the in-orbit performance of the instrument based on thePerformance Verification tests. PACS is fully operational, and the achievedperformance is close to or better than the pre-launch predictions.