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

The European Large Area ISO Survey (ELAIS) will provide Infrared observations of 4 regions in the sky with ISO. Around 2000 Infrared sources have been detected at 7 and 15 microns (with ISOCAM), 90 and 175 microns (with ISOPHOT)) over 13 square degrees of the sky. We present the source extraction pipeline of the 90 microns ISOPHOT observations, describe and discuss the results obtained and derive the limits of the ELAIS observational strategy.

The european large area iso survey - isophot results using the mpia-pipeline

ISO performed an extensive observing programme on the infrared zodiacal light, including multi-filter photometry of the global brightness distribution, observations of the asteroidal bands and cometary dust trails, and investigation of the small scale brightness fluctuation. The detailed determination of the spectral energy distribution of the zodiacal light, including mid-infrared spectrophotometry, opens the possibility for the separation of the main components of the infrared sky. The mid-infrared spectrum may provide information on the nature of the constituents, and on the size distribution of the interplanetary grains. Two years after the ISO mission we review the observations and summarize the results of ISOPHOT and ISOCAM.

Zodiacal light observations with the infrared space observatory

Discrete far-infrared (FIR) sources of M 31 are iden- tified in the ISO 175 m map and characterized via their FIR colours, luminosities and masses in order to reveal the nature of these knots. With our spatial resolution of 300 pc at M 31's distance, the FIR knots are clearly seen as extended objects with a mean size of about 800 pc. Since this appears too large for a single dust cloud, the knots might represent several clouds in chance projection or giant cloud complexes. The 175 m data point provides crucial information in addi- tion to the IRAS 60 and 100m data: At least two 2 modified Planckian curves with temperatures of about 40 K and 15-21 K are necessary to fit the spectral energy distributions (SEDs) of the knots. Though they show a continuous range of tem- peratures, we distinguish between three types of knots - cold, medium, warm - in order to recognize trends. Comparisons with radio and optical tracers show that - statistically - the cold knots can be identified well with CO and H I radio sources and thus might represent mainly molecular cloud complexes. The warm knots coincide with known H II regions and supernova remnants. The medium knots might contain a balanced mixture of molecular clouds and H II regions. The cold knots have a considerable luminosity and their discovery raises the question of hidden star formation. Though the optically dark dust lanes in M 31 generally match the FIR ring, surprisingly we do not find a convincing coincidence of our knots with individual dark clouds, which might therefore show mainly foreground dust features. The ratio of FIR luminosity to dust mass, L=M , is used to measure the energy content of the dust. It can originate from both the interstellar radiation field and still embedded stars recently formed. The knots have a clear L=M excess over the rest of M31, providing evidence that they are powered by star formation in addition to the interstellar radiation field. Furthermore, the L=M ratio of the warm knots is comparable to that of Galactic H II regions like M 42 or NGC 2024, while that of the cold knots still reaches values like in the average Orion complex. Thus both the

http://aa.springer.de/papers/0363003/2300917.pdf

The bright 175 mu m knots of the Andromeda galaxy

PACS covers the wavelength range 80-210 micrometers in spectrometric and photometric imaging modes. The long wavelength camera is a 16 X 25 pixel array of stressed Ge:Ga detectors. In order to demonstrate the feasibility of such a large array, one of the 25 linear arrays was manufactured. It consists of 16 elements of 1.5 mm3 each separated by ceramic plungers and stressed by one single mechanism. As preamplifier a dedicated CMOS circuit was developed, based on similar circuits successfully operating in ISO's photometer. In particular, it was intended to increase the gain of the CRE in order to minimize the debiasing effects on the low bias operated detectors. Two complete linear demonstrator arrays were manufactured and independently tested under various low background conditions in a 1.7 K environment at MPIA and MPE. The feasibility of the concept chosen was demonstrated in several functional tests. Valuable experience was gained to guide the development of the next generation of CREs and arrays.

FIRSA: the demonstrator array of the FIR camera for the photoconductor instrument PACS on ESA's FIRST satellite

We present maps of NGC 6946 at λ 61 and 205μm as well as scans through the galaxy at these and at 8 intermediate wavelengths. The bulk of the FIR luminosity arises from a diffuse disk component which extends beyond the 25mag/arcsec^2^ B isophote to at least the radius corresponding to the sensitivity limit. A FIR emission counterpart to the outlying HI disk is seen at both 61 and 205μm, for which a dust to HI mass ratio of 0.0046 is inferred from the 205μm brightness assuming a dust temperature of 15K. The disk scale length at both λ 61 and 205μm is similar to that seen in R-band.

Dietrich Lemke

Papers

The european large area iso survey - isophot results using the mpia-pipeline

Zodiacal light observations with the infrared space observatory

The bright 175 mu m knots of the Andromeda galaxy

FIRSA: the demonstrator array of the FIR camera for the photoconductor instrument PACS on ESA's FIRST satellite

ISOPHOT Maps of NGC 6946 in the range λ 60-200μm.