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The X-ray astronomy satellite BeppoSAX (Satellite per Astronomia X, “Beppo” in honor of Giuseppe Occhialini), is a project of the Italian Space Agency (ASI) with the participation of the Netherlands Agency for Aerospace Programs (NIVR). BeppoSAX was launched by an Atlas G-Centaur directly into a circular 600 km orbit at 3.9° inclination on April 30, 1996. The satellite is a three axis stabilized spacecraft with a total mass of about 1400 kg and main dimensions in flight configuration of about 2450 mm × 8980 mm × 3650 mm. The current (September 21, 2002) flight altitude is about 435 km and its uncontrolled re-entry is predicted late in 2002, or in 2003, with 26 kg of hydrazine on board that could not be vented or used for controlled re-entry due to the gyro package's total failure. Due to the relatively high mass of BeppoSAX, it must be expected that parts of the satellite will survive the re-entry into the Earth atmosphere. The Italian Space Agency has committed a study to analyse of the destructive phase of the uncontrolled atmospheric re-entry by means of a dedicated European software tool (SCARAB). The expected outputs will be used in order to determine how much of the spacecraft and how many fragments of it will reach the ground on the equatorial earth zone. This paper will address the peculiarities of the spacecraft's initial status, its risks at end of life, and the SCARAB modeling as well as its six dimension flight dynamics re-entry analysis results also in terms of the destruction history tree. Consideration will be made of the ground dispersion and casualty area due to the very restricted equatorial zone impacted.

The X-ray system GX339-4 has been observed on several occasions between March 1990 and September 1991 with the SIGMA hard X-Ray/soft gamma-ray imaging telescope (35 keV–1.3 MeV) on board the GRANAT observatory /1/. This object was detected in hard and soft states, as well as during a transition between these two states. We analyse the spectral and temporal behaviour of this black hole candidate.

The SIGMA telescope, the largest French scientific space-payload ever launched, is one of the main devices aboard the Soviet astronomy satellite GRANAT, successfully launched on December 1, 1989 from Baikonour, USSR. This high-energy space-telescope of unprecedented size, has been designed to produce high-resolution images of the hard X-ray and soft gamma-ray sky, in the energy range from 35 KeV to 1.3 MeV. After a comprehensive description of the instrument, a report is given on the most relevant characteristics of the telescope, including preliminary results from in-flight calibrations performed in the course of bright source observations.

Two currently operating international X-ray observatories MIR-KVANT and GRANAT are caring a number of coded mask telescopes with imaging capabilities in wide energy range from 2 up to 1300 keV. The Galactic Center region is the highest priority target for these instruments. Their results in 1988–1990 demonstrate the efficiency of coded mask telescopes observations in hard X-rays.

The region of the sky containing the Crab Nebula and its pulsar was observed by SIGMA several times during February and March, 1990. Data in the energy range 30–1300 keV were recorded in different functioning modes. One observation of ∼ 2 hours in timing mode allowed us to study the pulsed emission from PSR 0531+21. The pulsed signal has been detected up to ∼ 500 keV. We report here the results of the timing and spectral analysis of the data recorded in this observation.

The SIGMA telescope has been launched on December 1st 1989. After a calibration period, January and February 1990, the scientific observations started. In this paper, we review the first measurements obtained with SIGMA, and we give the preliminary highlights results obtained in the field of hard X-Ray/Gamma-Ray astronomy.