Herschel was launched on 14 May 2009, and is now an operational ESA space observatory o ering unprecedented observational capabilities in the far-infrared and submillimetre spectral range 55 671 m. Herschel carries a 3.5 metre 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 hours 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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Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy

The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submil- limetre 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 photom- etry in the 60−210 μm wavelength regime. In photometry mode, it simultaneously images two bands, 60−85 μ mo r 85−125 μ ma nd 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 afi eld 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.

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

We review progress over the past decade in observations of large-scale star formation, with a focus on the interface between extragalactic and Galactic studies. Methods of measuring gas contents and star-formation rates are discussed, and updated prescriptions for calculating star-formation rates are provided. We review relations between star formation and gas on scales ranging from entire galaxies to individual molecular clouds.

Star Formation in the Milky Way and Nearby Galaxies

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 mu m, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 mu m (447-1550 GHz) The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 03 K The photometer has a field of view of 4' x 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 26' The spectral resolution can be adjusted between 12 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 15-2

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The Herschel-SPIRE instrument and its in-flight performance

▪ Abstract This review surveys the observed properties of interstellar dust grains: the wavelength-dependent extinction of starlight, including absorption features, from UV to infrared; optical lum...

https://www.ifa.hawaii.edu/users/reipurth/reviews/draine.pdf

Interstellar dust grains

Four elds with areas ranging from 80 to 2000 arcmin 2 have been mapped with the photometer on board of the Infrared Space Observatory (ISO) at 90 and around 180m in regions of bright and faint cirrus. We examined the spatial characteristics of the infrared background emission with high spatial resolution and found that the fluctuations in the back- ground emission limit the detection sensitivity of ISOPHOT for most of our observations. At 90m the power law relation between the power in the fluctuations and the spatial frequen- cies established from IRAS data could be extended to twice as high spatial frequencies. At 180m the small-scale fluctua- tions were studied for the rst time by a cold space telescope with arcminute-resolution. A similar power law and spectral in- dex down to spatial scales of 3 0 as for the 90m component is found. For cirrus clouds the spatial frequency spectrum in the far-infrared has a similar shape as that derived from 21cm line observationsoftheinterstellarneutralhydrogen.Infaintregions the fluctuations are caused presumably by randomly distributed extragalactic sources. Future 3m class space telescopes survey- ing the sky around 200m will not be hampered by cirrus over most of the sphere.

ASTROPHYSICS Small-scale structures in the far-infrared background ?

The Mid-Infrared Instrument (MIRI) and the Near-Infrared Spectrograph (NIRSpec) of the JWST require various mechanisms for positioning optical elements in cryo-vacuum environment (7K resp. 35K): Wheels for exchanging filters, gratings and prisms, a flip mirror for switching between the sky and internal calibration sources and a linear actuator for refocusing purposes will have to be developed. In order to fulfill the stringent requirements of the mission, comprising to survive a warm ARIANE 5 launch, to guarantee high accuracy positioning in the cryovacuum with minimal power dissipation, to be operational with high reliability during 10 years of lifetime and to be testable under various environmental conditions, we propose a low cost and low schedule risk approach, based on the successful flight experience and qualification heritage from ESA’s infrared missions ISO and HERSCHEL.

Cryomechanisms for the instruments MIRI and NIRSpec on the James Webb Space Telescope (JWST)

ISOPHOT-S: Capabilities and Calibration.

Far Infrared observations of the Seyfert galaxies NGC 3227, NGC 4051 and NGC 4151 are presented. These are the first data from a complete sample of Seyfert galaxies that is being observed by ISO as part of the ISOPHOT guaranteed time. The new ISO data, in combination with the IRAS data, show that the mid to far IR emission in all three objects can be ascribed to two well defined regimes, namely a warm dust emitting region which we claim is heated by the emission from the respective active nuclei and a second colder emitting region which we attribute to dust heated in star forming regions.

Bimodal dust emission in three classical seyfert galaxies : ngc 3227, ngc 4051 and ngc 4151

Ces filtres ont ete concus pour etre utilises sur des telescopes spatiaux refroidis. Structure consistant en un reseau d'ouvertures en forme de croix dans une feuille metallique

Dietrich Lemke

Papers

ASTROPHYSICS Small-scale structures in the far-infrared background ?

Cryomechanisms for the instruments MIRI and NIRSpec on the James Webb Space Telescope (JWST)

ISOPHOT-S: Capabilities and Calibration.

Bimodal dust emission in three classical seyfert galaxies : ngc 3227, ngc 4051 and ngc 4151

IR resonant filters for the wavelength region 30-200 μm