We report the study of ISOGAL fields in the outer galactic bulge. We have combined 7 and 15 μm ISOCAM observations with DENIS IJKs near-infrared data to determine the nature of the sources and the interstellar extinction. Most of the ISOGAL sources show evolution of mass-loss rates in the range 10-8 to 10-6 M⊙/year. Most of the detected sources are red giants above the RGB tip; a few of them show an excess in and J - Ks-[15] colors. These sources are detected as AGB stars with large mass-loss rates.

Strip scanning measurements with crossing position angles have been carried out at 120 μm and 180 μm with the ISOPHOT instrument aboard ISO to observe extended FIR emission from six Abell clusters. The raw I120 μm/I180 μm surface brightness ratio including zodiacal light shows a bump towards Abell 1656 (Coma), dips towards Abell 262 and Abell 2670, and is without an unambiguous feature towards Abell 400, Abell 496, and Abell 4038. The subtraction of the zodiacal light leaves the bump towards Abell 1656 still present, while the dips towards Abell 262 and Abell 2670 are no longer discernible. This behavior can be reconciled in Abell 1656 with a localized excess of emitting material outside the Galaxy with properties different from the galactic foreground cirrus, and in Abell 262 and Abell 2670 with galactic cirrus structures localized on the line-of-sight to these clusters. At 120 μm the excess towards Abell 1656 (Coma) is ≈ 0.2 MJy/sr, with an integrated excess flux within the central region of 10'-15' diameter of ≈ 2.8 Jy. It is interpreted as being due to thermal emission from intracluster dust distributed in the hot X-ray emitting intracluster medium. Only a rough estimate of the associated dust mass of MD ≈ 107 M⊙ can be derived, since the dust temperature is poorly constrained. The visual extinction associated with this dust mass is negligible (AV << 0.1 mag) and much smaller than claimed from optical observations. No evidence for intracluster dust is found in the other five clusters observed. The rather low inferred dust mass in Abell 1656 together with the absence of a signature for intracluster dust in the other clusters observed indicates that intracluster dust is likely not responsible for the excess X-ray absorption seen in cooling flow clusters. These observations thereby represent a further unsuccessful attempt in detecting the presumed final stage of the cooling flow material, in accord with quite a number of previous studies. Finally, the observed dimming of the high - redshift supernovae is unlikely be attributable to extinction caused by dust in the intracluster or even a presumed intercluster medium.

This paper reviews what we know on the Extragalactic Background (EB) and on the nature of its contributing galaxies in the infrared (IR) and sub-millimeter (sub-mm). I first present the EB observationnal constraints, their main cosmological implications, and results from deep IR and sub-mm surveys. Then, using a phenomelogical model of IR galaxy evolution, I show how these data constrain the evolution of IR galaxies, in particular the luminosity density and the luminosity function. And finally, I briefly review the detection of the IR EB fluctuations and their potential implications.

Faint submillimeter sources detected with JCMT/SCUBA have faced an identification problem due to their broad beam profiles. Here we propose a new method to identify these sources at the mid-infrared utilizing a finer point spread function. ISOCAM has provided us a very deep 6.7 μm image of the Hawaii Deep Field SSA13. For all three 850 μm sources in this field, we have found their 6.7 μm counterparts. All of them have been identified with interacting galaxy pairs at the optical. Two of the pairs are very faint and red (I>24, I - K > 4), one of the two has the hard X-ray detection with Chandra. Assuming an Arp 220 SED, we have found a typical redshift of z ~ 2. This requires that the sources should be a few times more luminous than Arp 220. It appears that extremely high star formation rates are occurring in galaxies at high redshift with massive stellar contents already in place.

We present measurements of the fine structure transitions of atomic carbon, and of the submillimeter rotational lines of carbon monoxide in a variety of external galaxies. We discuss the relative contributions of atomic carbon and carbon monoxide for the cooling of molecular gas in these galaxies, and how these lines can be used to determine the physical conditions in the emitting gas.

The "Herschel Space Observatory" (formerly known as the "Far InfraRed and Submillimetre Telescope" - FIRST) is the fourth cornerstone mission in the European Space Agency (ESA) science programme. It will perform imaging photometry and spectroscopy in the far infrared and submillimetre part of the spectrum, covering approximately the 57-670 μm range. The key science objectives emphasize current questions connected to the formation of galaxies and stars, however, having unique capabilities in several ways, Herschel will be a facility available to the entire astronomical community. Because Herschel to some extent will be its own pathfinder, the issue of instrument calibration and data processing timescales has special importance. Herschel will carry a 3.5 metre diameter passively cooled telescope. The science payload complement - two cameras/medium resolution spectrometers (PACS and SPIRE) and a very high resolution heterodyne spectrometer (HIFI) - will be housed in a superfluid helium cryostat. Herschel will be placed in a transfer trajectory towards its operational orbit around the Earth-Sun L2 point by an Ariane 5 (shared with the ESA cosmic background mapping mission Planck) in early 2007. Once operational Herschel will offer a minimum of 3 years of routine observations; roughly 2/3 of the available observing time is open to the general astronomical community through a competitive proposal procedure.

The Cosmic Microwave Background Radiation is the oldest photon radiation that can be observed, having been emitted when the Universe was about 300 000 year old. It is a blackbody at 2.73 K, and is almost perfectly isotropic, the anisotropies being about one part to 100 000. However, these anisotropies, detected by the COBE satellite in 1992, constrain the cosmological parameters such as the curvature of the Universe. Archeops is a balloon-borne experiment designed to map these anisotropies. The instrument is composed of a 1.5 m telescope and bolometers cooled at 85 mK to detect radiation between 150 and 550 GHz. To lower parasitic signals, the instrument is borne by a stratospheric balloon during the arctic night. This instrument is also a preparation for the Planck satellite mission, as its design is similar to HFI. We discuss here the results of the first scientific flight from Esrange (near Kiruna, Sweden) to Russia on January 29th 2001, which led to a 22% (sub)millimetre sky coverage unprecedented at this resolution. Here, we put some emphasis on interstellar dust foreground emission observations.

The Japanese infrared space missions in the past and the future are briefly summarized with some historical and strategic view points. Starting with simple ground based observations, we have been putting an emphasis on space missions with less affected by the poor Japanese climate conditions for infrared observations using balloons, rockets and satellites. Focusing on diffuse infrared emissions, which are favorably observable by small and simple instruments, we have succeeded in getting unique results of zodiacal light, Galactic and extragalactic emissions as well as the cosmic background radiation.

The ASTRO-F (also known as Infrared Imaging Surveyor: IRIS) is the second infrared satellite mission of the Institute of Space and Astronautical Science, Japan to be launched early 2004 with the M-V rocket and is planned as a second generation infrared sky survey mission. It has a 67-cm aperture telescope and is cooled by 170-liter liquid helium and Stirling-cycle coolers. Two scientific instruments share the focal plane. The infrared camera (IRC) covers 2 to 26 μm range with large two-dimensional arrays in the imaging and low-resolution spectroscopic modes and will perform deep sky surveys of selected areas of the sky with a wide field of view (10' × 10') at unprecedented sensitivity. The far-infrared Surveyor (FIS), consisting of an imaging scanner and a Fourier transform spectrometer, covers 50 to 200 μm range and makes a whole sky survey in four far-infrared bands, which is higher by more than 10 in sensitivity (20-110 mJy), better by several in the spatial resolution (30''-50''), and longer in the spectral coverage (200 μm) than IRAS. A brief description and the current status of the ASTRO-F mission are presented.

The Stratospheric Observatory For Infrared Astronomy (SOFIA) is a 2.5 m telescope which will fly in a Boeing 747SP, commencing operation in late summer 2004. SOFIA is a joint American/German project and for most of this decade it will be the largest far-infrared telescope. SOFIA will have a suite of instruments available to the astronomical community, including the High-resolution Airborne Wide-band Camera (HAWC) - its facility far-infrared camera.

This paper presents the scientific objectives and technical aspects of the balloon-borne Experiment for Large Infrared Survey Astronomy (ELISA). The emphasis is put upon the synergies existing between the ELISA project and future space missions, both with respect to scientific and technical aspects. ELISA is a small balloon project for an experiment dedicated to measure the Far-Infrared to Sub-millimeter continuum emission of Galactic dust over a large fraction of the sky, with unprecedented sensitivity and angular resolution. The primary mirror of the telescope, similar to the one used for the Top-Hat mission, will have a diameter of 1 m, ensuring an angular resolution of about 3.5'. Bolometer arrays will be used in four photometric bands centered at 170, 240, 400, and 650 μm and providing a 22' × 45' instantaneous field of view per channel. A liquid He cryostat will host the cold optics, including the secondary mirror of the telescope, as well as the detectors, which will be cooled to 0.3 K using an 3He close-cycle fridge. Mapping of the sky will be accomplished by rotating the gondola over a large azimuth range (up to 60° amplitude). The pointing of the experiment will be maintained to a constant elevation during the azimuth scans through a feed back loop using the signal from a large format, fast stellar sensor, operating day and night. The scientific goal of the experiment is to map the diffuse Sub-millimeter emission along a large fraction of the Milky Way. The astronomical data obtained will be used to derive the emission properties of the dust grains in the Interstellar Medium (ISM), such as their temperature and emissivity. It will also allow to systematically measure the polarization of the dust emission. It should also lead to the detection of a few thousand point sources such as newly formed stars and distant galaxies. In addition to these goals, the ELISA project will serve as a test bed for the detector technology that will be used for the HERSCHEL space mission to be launched in 2007. The ELISA data will be made available to help calibrate the observations of HERSCHEL and PLANCK and to plan the large-scale surveys to be undertaken with HERSCHEL. Owing to these objectives, 3 flights of the ELISA experiment, are foreseen in the period from 2004 to 2006. The ELISA project is carried out by an international collaboration including France (CESR, IAS, CEA, CNES), The Netherlands (SSD/ESTEC), Denmark (DSRI), UK (Cardiff Univ.).

The Submillimetron is the international project of the space telescope for full sky survey in submillimeter region 0.15-1.5 mm using facilities of the Russian segment of the International Space Station (ISS). A free flying module for the project is under development in corporation Energia. Periodic docking of the module to the ISS gives possibility to combine low cost with reliability, refilling, repairment and maintenance. The concept of the telescope combines a 0.6 m mirror cooled to liquid helium temperature with a novel type of microbolometers arrays developed at Chalmers University (Sweden). This combination gives unique possibility to realize background limited sensitivity about 10-18 W/Hz-1/2 in the spectral minimum of the extraterrestrial background near frequency 1 THz between peaks of galactic dust emission and CMB. The angular resolution of the instrument is about 1 arcmin, field of view ~1°.

The balloon-borne submillimeter instrument PRONAOS has observed one square degree areas towards the Orion and M 17 molecular clouds. The 2'-3.5' resolution maps obtained in four wide wavelength bands between 200 μm and 600 μm, exhibit the dust distribution in these regions. We analyze the temperature and spectral index of the dust, and we show the anticorrelation between these two parameters. We derive estimations of the ISM column densities and masses in these regions.

We present initial results of a deep mid-infrared survey conducted in the high galactic latitude field SSA13 with ISO. We have surveyed through the broad band filter LW2 (5-8.5 μm) of the mid-infrared camera ISOCAM to probe the near-infrared light at high redshift. The 80% completeness limit for point sources in the central 6 arcmin2 reaches 10 μJy at 6.7 μm. 65 sources are detected down to 6 μJy in 16 arcmin2. The integral galaxy number counts are 1.4 × 104 deg-2 at 10 μJy with the slope of -1.5. The integrated 6.7 μm light down to 6 μJy is estimated as 0.43 nWm-2sr-1. Our counts are consistent with the results in the HDF and the model prediction based on the K band local luminosity function. It suggests that the majority of the detected sources are E/S0 galaxies at z>1.

Although ground-based submm facilities have been operating since more than a decade now, very few information has been collected at the lower frequencies offered by Herschel. Additional observations need to be conducted prior to launch to assess the reliability of a given source to be used as calibrator for photometry and/or spectroscopy. In this paper we present some of the drivers for the preparation of such a database on the basis of pioneering and long-term observing campaigns.

Compact Antenna Test-Ranges (CATR) represent a high standard of state-of-the-art test facilities with a fast and real time measurement capability up to the sub-millimeter range. Future scientific observation instruments of ESA such as the Planck and Herschel telescopes are working within this frequency ranges and require a high measurement accuracy for large antenna apertures. This present paper shows the first modelling of a large CATR at millimetre frequency. The software used in this paper is GRASP8 (from TICRA), and specially the recent Multi-Reflector Geometrical Theory of Diffraction upgrade (MR-GTD thereafter).

We present the results of an experimental study of the structural effects induced by Lyman-α UV photons in crystalline water ice at low temperature carried out by using in situ infrared spectroscopy. We studied the evolution, under UV irradiation, of the 3 micron band profile. We found that an UV dose of few eV per water ice molecule is enough to fully amorphize the structure at the investigated temperature of 16 K. The evolution of the 3 micron feature during UV irradiation is compared with that observed for fast ion irradiation carried out in the same experimental set-up. Both photons and fast ions are present in space, they can induce variations in the profile of the 3 micron band of crystalline water ice. Thus these effects must be considered when one attempts to deduce, from the profile of the observed ice band, information on the temperature history of the responsible dust.

We present an extinction map of the Polaris molecular cirrus cloud derived from star counts and compare it with the Schlegel et al. [13] extinction map derived from the far-infrared dust opacity. We find that, within the Polaris cloud, the Schlegel et al. [13] AV values are, on average, a factor 2 higher than the star count values. We propose that this discrepancy results from a difference in τFIR/AV between the diffuse atomic medium and the Polaris cloud. We use the difference in spectral energy distribution, warm for the diffuse atomic medium, cold for the Polaris cloud, to separate their respective contribution to the line of sight integrated infrared emission and find that the τFIR/AV of cold dust in Polaris is on average 4 times higher than the Schlegel et al. [13] value for dust in atomic cirrus. This change in dust property could be interpreted by a growth of fluffy particles within low opacity molecular cirrus clouds such as Polaris. Our work suggests that variations in dust emissivity must be taken into account to estimate AV from dust emission wherever cold infrared emission is present (i.e. molecular clouds).

This paper reports the first results obtained on the photodissociation of the isolated PAH cations 12C24H+12, 13C12C23H+12 and 12C24H+10, using the astrochemistry experimental set-up PIRENEA. The dissociation patterns of these ions involve the loss of pairs of hydrogen atoms. A first interpretation indicates that the -H2 dissociation path is favoured compared to the -H path in our experimental conditions. These results might have important implications on the formation of H2 in the interstellar medium.