B. Melchiorri

MITO: the 2.6 m millimetre telescope at Testa Grigia

Abstract We describe a new ground based telescope dedicated to millimetre cosmological research: MITO, Millimetre and Infrared Testagrigia Observatory. The site and all the instrumental subsystems of the telescope have been chosen to perform high sensitivity measurements for wavelengths ranging from 300 micron to 2 millimetre. The possibility of detecting fluctuations of the Cosmic Microwave Background has been explored for some observational strategies. F. Melchiorri

A ground-based experiment for CMBR anisotropy observations: MITO

Ground-based observations at millimeter wavelengths are still competitive with space observatories if inevitable foreground contamination is considered at all stages of data acquisition and analysis. Technical solutions together with carefully chosen cosmological targets and observational strategies are the key points in the development of the MITO experiment.

Testing the isotropy of the cosmic microwave background - the ULISSE Experiment

The balloon-borne experiment ULISSE, operating at millimetric wavelengths, set a very stringent upper limit to the differential (single-subtracted) cosmic microwave background anisotropy at 6-degrees: DELTA-T less than or similar 35-mu-K. This limit is obtained with a likelihood-ratio analysis; the size and power of the test are 5% and less than or similar 80%, respectively. We discuss the implications of this upper bound for flat cold dark matter and open baryonic-dominated cosmologies.

The BOOMERANG experiment

The BOOMERANG (Balloon Observations Of Millimetric Extragalactic RAdiation aNd Geophysics) experiment is an international effort to measure the Cosmic Microwave Background (CMB) anisotropy on angular scales of 20′ to 4°, with unprecedented sensitivity, sky and spectral coverage. The telescope will be flown from Antarctica by NASA-NSBF with a long duration stratospheric balloon (7–14 days), and is presently scheduled for flight in 1995–1996. The experiment is designed to produce an image of the Cosmic Microwave Background with high sensitivity and large sky coverage. These data will tightly constrain the baryon density, the reionization history, and the formation of large-scale structure in the universe. BOOMERANG will test technologies and return science data that are essential to the design of a future space-borne mission to map CMB anisotropy.

Atmospheric transmission and noise measurements in Antarctica

Abstract We describe a set of measurements carried out in Antarctica during the second Italian Antarctic Expedition. Atmospheric precipitable water vapour, millimetric transmission and noise were monitored for 2 months during the austral summer. The results suggest that the site is favourable for far infrared astronomy measurements.

The dipole anisotropy of the cosmic microwave background radiation

Abstract We review the prediction, discovery and precise measurements of CMB Dipole Anisotropy, a field in which Dennis Sciama has provided important initial insight.

LIMITATIONS TO THE ACCURACY OF COSMIC BACKGROUND RADIATION ANISOTROPY MEASUREMENTS: ATMOSPHERIC FLUCTUATIONS

We discuss the ultimate limits posed by atmospheric fluctuations to observations of cosmic background anisotropies (CBAs) in ground-based and balloon-borne experiments both in the radio and millimetric regions. We present correlation techniques useful in separating CBAs from atmospheric fluctuations. An experimental procedure is discussed for testing a site in view of possible CBA observations. Four sites with altitudes ranging from 0 up to 3.5 km have been tested.

Non-polarizing far-infrared filters

Abstract Polyethylene embedded with glass microspheres has shown the same optical properties as Fluorogold™ in the far-infrared. The polarizing properties of Fluorogold (laminated in thin foils) are avoided by pressing the polyethylene/glass powder between hot plates. The new fiters are suitable for long-wave pass filters with intrinsic polarization less than 10−4

The TIR project: A balloon telescope for the measurement of CBR anisotropies

We describe the TIR telescope: a 2.6 m telescope which can be carried to balloon altitude, to perform far infrared (FIR) and millimetric (mm) observations. The telescope has been optimized for the search of Cosmic Background Radiation (CBR) Anisotropies and of faint, diffuse mm and FIR sources. We illustrate the scientific problems which this system can deal with and the technical solutions which were considered during the project. Flight experience with a smaller (1.2 m) prototype (the ARGO 1989 telescope) is also described.

MITO: a procedure for CBA measurements and a search for cosmic strings

SummaryMITO (Millimetric and Infrared Testa Grigia Observatory) is a 3 m telescope dedicated to the study of Cosmic Background Anisotropies. It is located at 3500 m above sea-level at Plateau Rosa, Cervinia. We describe the Observatory and discuss two on-going research programs: a clearning procedure in order to remove galactic dust signals from cosmological data and a search for cosmic strings toward double-lensed quasars. Both the programs will be carried out by means of a He-3 photometer operating at the frequencies of 5, 10, 12, 30 cm−1.