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COCHISE is a 2.6 meter millimetric telescope, mainly devoted to cosmological observations, located at Concordia. In this paper we report on the installation phases and preliminary operations performed with this instrument. At present, COCHISE is the largest telescope located at Concordia, for that reason it represents a pathfinder for future telescopes.

Published in: Astrophys. J. 513 (1999) 23 citations recorded in [Science Citation Index] Abstract: We report simultaneous observations at 1.2 and 2 mm, with a double channel photometer on the SEST Telescope, of the X-ray cluster RXJ0658-5557 in search for the Sunyaev-Zel'dovich (S-Z). The S-Z data were analyzed using the relativistically correct expression for the Comptonization parameter and we find from the detected decrement (2.60 +/- 0.79) ~ 10^{-4}, which is consistent with that computed using the X-ray (ROSAT and ASCA) observations. The uncertainty includes contributions due to statistical uncertainty in the detection and systematics and calibration. The 1.2 {mm} channel data alone gives rise to a larger Comptonization parameter and this result is discussed in terms of contamination from foreground sources and/or dust in the cluster or from a possible systematic effect. We then make use of the combined analysis of the ROSAT and ASCA X-ray satellite observations to determine an isothermal model for the S-Z surface brightness. Since the cluster is asymmetrical and probably in a merging process, models are only approximate. The associated uncertainty can, however, be estimated by exploring a set of alternative models. We then find as the global uncertainty on the Comptonization parameter a factor of 1.3. Combining the S-Z and the X-ray measurements, we determine a value for the Hubble constant. The 2 mm data are consistent with H_0(q_0 = 1/2)= 53^{+38}_{-28} km/s Mpc^{-1}, where the uncertainty is dominated by the uncertainty in models of the X-ray plasma halo.

The need for accurate and complete maps of the galaxy at radio frequencies is made evident not only by the importance of the data in the study of galactic dynamics and structure formation but also in the analysis of cosmic background radiation data. A summary of the existing radio surveys of our galaxy is presented along with their limitations. A new program, the Galactic Emission Mapping (GEM) project, to obtain calibrated and complete maps of the galaxy in the 400 to 1400 MHz range, is outlined.

COCHISE (Cosmological Observations at Concordia with High-sensitivity Instrument for Source Extraction) is a 2.6 m telescope located on the high Antarctic Plateau near the Italian-French Concordia Base. The telescope is mainly devoted to Cosmological observations, able to operate between 200 mu m and 3 mm of wavelength. In this paper we describe the main characteristics of the instrument. We also report on the first light, obtained during summer 2010-2011: this result marks the beginning of millimetre astrophysical observations at Concordia. Responsivity, noise equivalent temperature and field of view of the instrument are reported. At present COCHISE is the largest telescope located at Concordia. Beside the scientific expectations, the use of this kind of instrument in the Antarctic environment poses technological aspects of relevant interest: thus COCHISE can be considered as a pathfinder for future Antarctic telescopes.

OASI (Infrared and Sub-mm Antarctic Observatory) is the first large telescope permanently installed in Antarctica. It is located close to the Italian Base in Antarctica (Terra Nova Bay Station, latitude: 74.39 S, longitude: 164.09 E). The OASI first light was received in December 1990 when the wobbling secondary mirror was mounted. The telescope is planned to be an open facility which can operate in the wavelengths range between 350 μm and 3mm. The sky coverage from OASI goes down to a declination of about-35° for a 24 hours/day observing time.

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We report on millimetric continuum observations of two bright compact H II regions, which have been observed for the first time in this frequency range. For the two observed regions (G291.6-0.5 and G291.3-0.7), we derive the flux densities at the two observed wavelengths (1.25 and 2 mm) as well as the spectral index and the temperature of the surrounding dust by fitting a modified blackbody curve to our results combined with IR values obtained from the literature. We also estimate the dust mass and the bolometric luminosity of the two regions.

COMPASS (COsmic Microwave Polarization at Small Scale) is an experiment devoted to measuring the polarization of the CMBR. Its design and characteristics are presented.

A balloon-borne experiment has been conceived in order to map the sub-millimetric galactic emission at four different wavelengths between 400 μm and 2 mm at an angular scale of 1°. Such measurements will make it possible both to investigate the nature of the interstellar dust and to disentangle the galactic contribution from extragalactic and cosmological signals. A binocular telescope system has been realized by means of two 37 cm of-axis wobbling parabolic mirrors, each one coupled with a two-channel 3He photometer. The first trans-Mediterranean flight is scheduled for summer 1995.

A double channel (1.2 and 2 mm) photometer has been installed at the focus of the 15m SEST antenna in Chile to perform measurements of the Sunyaev-Zeldovich effect towards X-ray ROSAT clusters. This paper describes the instrument and the characteristics of the system: its sensitivity, field of view, noise and the performed calibrations.

We have considered some millimetric observations of our Galaxy and of the Large Magellanic Cloud (LMC) taken at the Italian Base in Antarctica. Using other submm data and fitting all the observations with a modified Planck curve, we have obtained useful information about the temperaureT and the spectral index α of the dust grains both for the Galaxy and the LMC. For the galactic spectrum two different couples ofT and α match the detected fluxes:a)T=7K, α=2;b)T=15K, α=1.1. We have tried to identify the nature of the dust grains responsible for the submm and mm emission by comparing these results with the spectral trend of some cosmic analogues studied in laboratory.

During the austral summer 1987/88 and 1989/90, we performed two Antarctic expeditions with the main purpose of installing the first permanent Antarctic Infrared Observatory O.A.S.I. (Osservatorio Antartico Sub-millimetrico Infrarosso). At the same time, using two small telescope (100 cm and 48 cm diameter1,2), we measured the continuum emission at millimetric wavelengths of the Large (LMC) and Small (SMC) Magellanic Clouds. In both the expeditions, we detected a strong signal, both at 1mm and 2mm wavelengths, coming from the LMC and SMC. These signals are very well spatially correlated with the 100 μm IRAS data. The resulting spectra on LMC and SMC indicate a gray-body emission from cold dust at a temperature T d = 15K and a spectral index α = 1.1. The longwavelength part of the spectrum shows an excess in the emission (Fig. 1) from the cool dust. A possible explanation of both the FIR and the mm measurements could be the follow: since the mm data and the FIR data are well spatially correlated, it is likely that the emitting source is defined in the same sky region, while the emitting dust is made of two different components. The first component, responsible of the FIR emission, is a dust at a temperature of 33 K and a spectral index α = 2. The second component is a cold dust at a temperature of about 15 K and a spectral index α = 1.1. Following Chini et al., we can also fit the longwavelength part of the spectrum with only the 100 μm IRAS data. In this case, we obtain a dust temperature of 17 K with α = 1.2. An additional consideration on this model, following Stark could be done. In the LMC spectrum, the IRAS 60 μm point is contaminated by the contribution of fine structure radiation of neutral oxygen at 63 μm for an amount of 0.1 − 0.7 MJy srad−1. After the necessary correction, the 60 μm IRAS point is reduced in intensity, fitting better the 17 K model.

Millimetric continuum observations of the Galactic disk at b about -8 deg and l about 290-310 deg has been achieved during the Italian 1987-1988 scientific expedition in Antarctica. Emission was detected from few southern clouds (the Chamaeleon region and a cirrus cloud), and their energy distributions reveal an excess in the long wavelength range. This fact is interpreted as being due to the presence of a cold component of the interstellar material coexisting with the warm dust responsible for the emission detected by IRAS. Then, a multiple nature of the interstellar dust is suggested also in regions far from the Galactic bulge. 45 refs.

In this paper we report the results of an experiment on the CBR anisotropy at 2 mm and 2.5 degrees angular resolution carried out during the Antarctic summer of 1987−88. We find evidence of statistical fluctuations at a level of T/T=2x10−4, most of which can be ascribed to both atmos pheric residual noise and/or patch galactic emission. In addition, we observed the Magellanic Clouds and obtained an excess of mm−wave radiation in dicating the presence of a cold dust component coexisting with the IRAS wa rm dust. (AIP)

Millimetric observations (1-2 mm) toward the Magellanic Clouds from Antarctica show a good spatial correlation with the IRAS 100-micron emission in the same sky regions. Very likely a cold component coexisting with the warm dust detected by IRAS has been observed. 18 refs.

We show how combined large-beam infra-red and radio observations toward the Virgo Cluster may be explained by assuming the existence of a large tepid halo surrounding the giant galaxy M87. Such a halo would be able to close the cluster gravitationally. If interpreted as being due to bremmstrahlung radiation by a tepid extended halo, it also explains the infra-red observations, and it has important implications for the physics of M87.

The polarization of the Sun's radiation has been measured in the 30-10 cm −1 spectral region through the atmospheric windows at the high altitude observatory of Testa Grigia, Italy, at 3500 m a.s.l. The results are in agreement with those previously obtained during a balloon flight in the 100-5 cm −1 region. The spectral dependence of the linearly polarized component has been investigated and a possible interpretation of the obtained data is suggested.

The possibility of detecting diffuse sky radiation in the (250÷3000) μm range is discussed on the basis of recent measurements performed at the mountain observatory of Testa Grigia (3500 m a.s.l.) on the atmospheric emission and on the atmospheric noise. It is shown how, in many cases, the limits assigned by the residual atmospheric emission are well below the sensitivity of the available infra-red detectors; as a consequence some new experiments of background astronomy are suggested.

We present the results of a balloon flight devoted to the observation of the diffuse sky radiation in the wave-length region (150÷400) and (350÷3000) μm, at angular scales larger than six degrees. Observations of dust emission and distribution are discussed.

If we look at the infrared sky between 1 and 1000 µm we observe several contributions to the background coming from different parts and/or epochs of the universe. We consider the problem of distinguishing between ‘local’ contributions (planetary and galactic dust, atmospheric emission, dashed lines) and the extragalactic backgrounds. In the figure are shown the computed emissions for rich clusters of galaxies (IRG) and integrated infrared galaxies (IRG). CMB is the cosmic microwave background.

During 1978 balloon borne infrared experiment we observed a signal coming from Virgo Cluster (see Ceccarelli et al., 1982).

We have developed a large beam, five-band IR differential photometer, covering the range from 10 to $ 200 μm, devoted to the study of diffuse emission of galactic and extragalactic origins. Here we describe in detail the main features of the experimental apparatus and its calibration. The experiment was flown on a stratospheric balloon on 30 July 1984, collecting data for about 15 hours.

Results concerning zodiacal dust emission are reported from an IR sky survey experiment performed during a balloon flight on July 30, 1984 which explored five wavelength bands centered at 11, 19, 50, 108, and 225 microns. The dust density n decreases at a rate slower than r exp -1.3 with increasing heliocentric distance. The trend of n depends critically on the radial variation of the temperature which, in turn, depends on the chemical composition of the grains. The spatial distribution of the dust is in good agreement with that previously inferred from IR measurements. A comparison between IR and optical observations points out the uncertainties affecting the estimates of the dust density obtained with both methods. The emission spectrum of the dust is used to discriminate among the different species of grains, showing that the observations can be accounted for by an appropriate mixture of graphite and silicates. 18 references.

We present preliminary results from a ground-based experiment carried out in Antarctica and devoted to the search for the Cosmic Background Radiation (CBR) anisotropics. We find an upper limit of\( \frac\Delta TT < 2 \cdot 10 - 4 \) at 2.5° angular scale and at 2 mm wavelength.

It is well known that the two darkest clouds in the sky are located in the regions of ρ-Ophiuchus (1″=354°; b″=160) and Taurus (1″=174°; b″=−13°). The approximate simmetry of these two regions around the Sun has suggested that they may be linked by a very elongated cylindrical cloud. Indirect evidence supporting this view has been obtained by studying the colour excess of nearby stars and the relation between galaxy counts and HI column density (Turon and Menessier, 1975; Lebrun, 1979).

An experiment has been developed in order to map the submillimetre Galactic emission at four different wavelengths between 400 μm and 2 mm at an angular scale of 1°. A binocular telescope system has been realised by means of two off-axis wobbling parabolic mirrors, each one coupled to a two-channel 3He photometer. A first run of observations from Dome C is planned for the Antarctic summer 1995–96.

An infrared search for the Sunyaev-Zeldovich effect toward the intergalactic ''void'' discovered by Kirshner et al. has given a null result within 1 x 10/sup -4/ K at 1 standard deviation. The result implies that the change of the Comptonization parameter toward the hole is less than 2 x 10/sup -2/. From the hypothesis that the hot gas is absent in the hole, we get an upper limit 0.5 for the normalized density of the extragalactic gas.

A ground-based experiment has been carried out in Terra Nova Bay, Antarctica in order to detect anisotropies in cosmic background radiation at an angular scale of 1.3 deg. A 1-m-diameter flux collector and an He-3-cooled bolometric detector sensitive to radiation with a wavelength between 1.86 and 2.34 mm are used. Observations were carried out during the Antarctic summer and are limited by atmospheric emission fluctuations. 13 references.