Letter to the Editor

The Herschel-SPIRE instrument and its in-flight performance^*

¹ Institut d'Astrophysique Spatiale, Université Paris-Sud 11, 91405 Orsay, France
² ESA Herschel Science Centre, ESAC, Villaneuva de la Cañada, Spain
³ School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA, UK
⁴ Commissariat à l'Énergie Atomique, Service d'Astrophysique, Saclay, 91191 Gif-sur-Yvette, France
⁵ Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7, 2AZ, UK
⁶ NASA Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
⁷ UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁸ Laboratoire d'Astrophysique de Marseille, UMR6110 CNRS, 38 rue F. Joliot-Curie, 13388 Marseille, France
⁹ University College London, Department of Physics and Astronomy, Gower Street, London WC1E 6BT, UK
¹⁰ University College London-Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
¹¹ Cornell University, Ithaca, NY 14853, USA
¹² Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
¹³ Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, La Laguna, Tenerife, Spain
¹⁴ Istituto di fisica dello Spazio Interplanetario, Fosso del Cavaliere 100, 00133 Roma, Italy
¹⁵ National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, PR China
¹⁶ Commissariat à l'Énergie Atomique, INAC/SBT, 17 rue des Martyrs, 38054 Grenoble, France
¹⁷ Institut de Radioastronomie Millimétrique, 300 rue de la Piscine, 38406 Saint-Martin d'Hères, France
¹⁸ Joint Astronomy Centre, 660 N. A'ohoku Place, University Park, Hilo, Hawaii 96720, USA
¹⁹ University of Padua, Dipartimento di Astronomia, vicolo Osservatorio, 3, 35122 Padova, Italy
²⁰ Blue Sky Spectroscopy Inc., Suite 9-740 4th Avenue South, Lethbridge, Alberta T1J 0N9, Canada
²¹ University of Colorado, Dept. of Astrophysical and Planetary Sciences, CASA 389-UCB, Boulder, CO 80309, USA
²² European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
²³ California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA
²⁴ ESA ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
²⁵ NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
²⁶ NASA Herschel Science Centre, IPAC, 770 South Wilson Avenue, Pasadena, CA 91125, USA
²⁷ Observatoire de Paris, LESIA/CNRS, 5 place J. Janssen, 92195 Meudon, France
²⁸ Centre National d'Études Spatiale, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France
²⁹ University of Lethbridge, Institute for Space Imaging Science, Department of Physics and Astronomy, Lethbridge, Alberta T1K 3M4, Canada
³⁰ University of Sussex, Dept. of Physics and Astronomy, Brighton BN1 9QH, UK
³¹ Stockholm University, Dept. of Astronomy, AlbaNova University Center, Roslagstullsbacken 21, 10691 Stockholm, Sweden
³² University of Manchester, School of Physics and Astronomy, Manchester, M13 9PL, UK
³³ Institut d'Astrophysique de Paris, UMR7095, UPMC, CNRS, 98bis Bd Arago, 75014 Paris, France
³⁴ University of Hertfordshire, Centre for Astrophysics Research, College Lane, Hatfield, Herts AL10 9AB, UK
³⁵ Dept. of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
³⁶ McMaster University, Dept. of Physics and Astronomy, Hamilton, Ontario, L8S 4M1, Canada

Received: 26 March 2010
Accepted: 21 April 2010

Abstract

The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194–671 μm (447–1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4´× 8´, observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6´. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5–2.