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Instruments on Herschel

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Herschel carries a suite of three scientific instruments consisting of a combination of cameras to make infrared images and spectrometers which analyze the emission from sources of infrared radiation over a wide wavelength range to build up a spectrum of the emitted radiation.
The three instruments are:

  • SPIRE - The Spectral and Photometric Imaging Receiver
  • PACS - Photodetector Array Camera and Spectrometer
  • HIFI - Heterodyne Instrument for the Far Infrared

See ESA's Herschel Instruments in depth for more details.




SPIRE InstrumentThe SPIRE instrument consists of 3 cameras and a Fourier Transform Spectrometer and is the long-wavelength instrument on-board Herschel. The three cameras take images in 3 infrared colours corresponding to the wavelengths of 250 micrometres, 350 micrometres and 500 micrometres. Images from the 3 cameras can be combined to make multi-colour images. The cameras can either be used to focus on a small point-like astronomical source or alternatively they can be scanned across the sky to build up large area maps. The SPIRE spectrometer covers the wavelength range from 200-670 micrometres and is capable of resolutions of factors of 20-1000.




The PACS instrument consists of 2 cameras and 2 spectrometers and is the short-wavelength on-board Herschel. The PACS cameras have a choice of taking an image in one of two wavelength bands, of either 60-90 micrometres or 90-130  micrometres  together simultaneously with another wavelength band at 130-210  micrometres. The spectrometer also covers the wvaelength range from 60-210 micrometres, right up to where the SPIRE spectrometer wavelength coverage begins.




The HIFI instrument is a super accurate spectrometer of a special kind. HIFI is a heterodyne spectrometer and measures high frequency astronomical signals then mixes them with a very stable monochromatic signal, generated within the instrument itself. The resulting difference signal is then processed.  HIFI observes over the wavelength range from 157-625 micrometres in seven infrared wavelength bands.