Cryogenic far-infrared laser absorptivity measurements of the Herschel Space Observatory telescope mirror coatings

Fischer, J.; Klaassen, T.O.; Hovenier, N.; Jakob, Gerd; Poglitsch, A.; Sternberg, Oren

doi:10.1364/ao.43.003765

Cited by 29 publications

(34 citation statements)

References 7 publications

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“…The measured glitch rates on the different PACS detectors were compatible with expectations at solar minimum (Ge:Ga photoconductors: 0.08−0.2 hits/s/pixel; Bolometers: ∼1 hit/min/pixel). The observed far-infrared telescope background, mainly determined by M1 and M2 temperatures and the telescope emissivity (see Fischer et al 2004) was very close to predictions during the first PACS spectrometer measurements.…”

Section: In-orbit Performancesupporting

confidence: 79%

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

Poglitsch¹,

Waelkens²,

Geis³

et al. 2010

A&A

1,986

797

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The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16 × 25 pixels, each, and two filled silicon bolometer arrays with 16 × 32 and 32 × 64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60−210 μm wavelength regime. In photometry mode, it simultaneously images two bands, 60−85 μm or 85−125 μm and 125−210 μm, over a field of view of ∼1.75 × 3.5 , with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47 × 47 , resolved into 5 × 5 pixels, with an instantaneous spectral coverage of ∼ 1500 km s −1 and a spectral resolution of ∼175 km s −1 . We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the performance verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions. Key words. space vehicles: instruments -instrumentation: photometers -instrumentation: spectrographsHerschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

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Section: In-orbit Performancesupporting

confidence: 79%

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

Poglitsch¹,

Waelkens²,

Geis³

et al. 2010

A&A

1,986

797

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“…The secondary is a single piece, machined with an integral "scattercone" to suppress standing waves and the narcissus effect. The M1 and M2 optical surfaces have been coated with a high reflectivity/low emissivity (Fischer et al 2004) aluminium layer, covered by a thin protective "plasil" (silicon oxide) coating which allows cleaning.…”

Section: Telescopementioning

confidence: 99%

HerschelSpace Observatory

Pilbratt¹,

Riedinger

Paßvogel

et al. 2010

A&A

3,000

2,873

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Herschel was launched on 14 May 2009, and is now an operational ESA space observatory offering unprecedented observational capabilities in the far-infrared and submillimetre spectral range 55-671 μm. Herschel carries a 3.5 m diameter passively cooled Cassegrain telescope, which is the largest of its kind and utilises a novel silicon carbide technology. The science payload comprises three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI, whose focal plane units are housed inside a superfluid helium cryostat. Herschel is an observatory facility operated in partnership among ESA, the instrument consortia, and NASA. The mission lifetime is determined by the cryostat hold time. Nominally approximately 20 000 h will be available for astronomy, 32% is guaranteed time and the remainder is open to the worldwide general astronomical community through a standard competitive proposal procedure.

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“…The calibration is based on observations of a dark region of sky, i.e., where the detectors should only be receiving thermal radiation from the Herschel telescope and SPIRE instrument. Models of the telescope and instrument emission are constructed using onboard temperature sensors and the telescope mirror emissivity as measured on the ground (Fischer et al 2004), as described in the SPIRE observer's manual (2011). The spectral response applicable to extended sources is then defined as,…”

Section: Extended and Point Source Calibration Of The Ftsmentioning

confidence: 99%

Observing extended sources with theHerschelSPIRE Fourier Transform Spectrometer

Polehampton

Etxaluze

et al. 2013

A&A

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The Spectral and Photometric Imaging Receiver (SPIRE) on the European Space Agency's Herschel Space Observatory utilizes a pioneering design for its imaging spectrometer in the form of a Fourier Transform Spectrometer (FTS). The standard FTS data reduction and calibration schemes are aimed at objects with either a spatial extent that is much larger than the beam size or a source that can be approximated as a point source within the beam. However, when sources are of intermediate spatial extent, neither of these calibrations schemes is appropriate and both the spatial response of the instrument and the source's light profile must be taken into account and the coupling between them explicitly derived. To that end, we derive the necessary corrections using an observed spectrum of a fully extended source with the beam profile and considering the source's light profile. We apply the derived correction to several observations of planets and compare the corrected spectra with their spectral models to study the beam coupling efficiency of the instrument in the case of partially extended sources. We find that we can apply these correction factors for sources with angular sizes up to θ D ∼ 17 . We demonstrate how the angular size of an extended source can be estimated using the difference between the subspectra observed at the overlap bandwidth of the two frequency channels in the spectrometer, at 959 < ν < 989 GHz. Using this technique on an observation of Saturn, we estimate a size of 17.2 , which is 3% larger than its true size on the day of observation. Finally, we show the results of the correction applied on observations of a nearby galaxy, M82, and the compact core of a Galactic molecular cloud, Sgr B2.

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Cryogenic far-infrared laser absorptivity measurements of the Herschel Space Observatory telescope mirror coatings

Cited by 29 publications

References 7 publications

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

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

HerschelSpace Observatory

Observing extended sources with theHerschelSPIRE Fourier Transform Spectrometer

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