In-flight characterisation of Herschel-SPIRE optical performances

The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on ESA's Herschel Space Observatory, launched in May 2009 and now orbiting L2. This long wavelength instrument covers 200 to 670 microns with a three band photometric camera and a two band imaging Fourier Transform Spectrometer. We discuss the in-band SPIRE optical performances as obtained from measurements made during in-orbit Commissioning and Performances Verification Phases. Complementary to the characterization of the instrument spectral characteristics, attention is focused here on a set of dedicated observations made of unresolved bright sky targets mainly obtained through the use of standard operating mode such as scan mapping. These tests were aimed at measuring the geometry of the respective Photometer and Spectrometer field-of-views as well as the spatial response of the end-to-end optical chain, from telescope to focal plane detectors in all spectral bands. Implications for instrument flight calibration parameters are reported. Finally comparison with model-based results from design & build expectations and previously reported ground-measured characteristics is given before concluding on the excellent state of the in-flight Herschel/SPIRE optical performances; one of the key factors in the realization of the full scientific potential of the Herschel observatory in the SPIRE spectral bands.

[1]  James J. Bock,et al.  Status of the SPIRE photometer data processing pipelines during the early phases of the Herschel Mission , 2010, Astronomical Telescopes + Instrumentation.

[2]  Kjetil Dohlen,et al.  Imaging FTS for Herschel SPIRE , 2003, SPIE Astronomical Telescopes + Instrumentation.

[3]  L. Mandel,et al.  Optical Coherence and Quantum Optics , 1995 .

[4]  Marc Ferlet,et al.  In-orbit performance of the Herschel/SPIRE imaging Fourier transform spectrometer , 2010, Astronomical Telescopes + Instrumentation.

[5]  Kevin Xu,et al.  The data processing pipeline for the Herschel/SPIRE imaging Fourier Transform Spectrometer , 2008, Astronomical Telescopes + Instrumentation.

[6]  H. Roussel,et al.  In-flight calibration of the Herschel-SPIRE instrument , 2010, 1005.5073.

[7]  Matthew Joseph Griffin.  Herschel-SPIRE: Design, In-Flight Performance and Scientific Capabilities , 2010 .

[8]  Peter Ade,et al.  Herschel-SPIRE: design, ground test results, and predicted performance , 2008, Astronomical Telescopes + Instrumentation.

[9]  Marc Ferlet,et al.  Imaging at low Fresnel number: some challenges and applications , 2006, SPIE Optics + Photonics.

[10]  G. Chattopadhyay,et al.  Feed horn coupled bolometer arrays for SPIRE - design, simulations, and measurements , 2003 .

[11]  Kjetil Dohlen,et al.  Optical design of the SPIRE instrument for FIRST , 2000, Astronomical Telescopes + Instrumentation.

[12]  J. W. Bowen,et al.  Long-wave optics , 1993 .

[13]  Kjetil Dohlen,et al.  Characterisation of Herschel-SPIRE flight model optical performances , 2008, Astronomical Telescopes + Instrumentation.

[14]  S. Ott,et al.  Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy , 2010, 1005.5331.

[15]  B. P. Crill,et al.  Measuring Planck beams with planets , 2010, 1007.3468.

[16]  S. J. Liu,et al.  Herschel : the first science highlights Special feature L etter to the E ditor The Herschel-SPIRE instrument and its in-flight performance , 2010 .