The SAX mission for wide-band X-ray astronomy

The SAX (Satellite per Astronomia X) mission is a major joint program of the Italian Space Agency (ASI) and the Netherlands Agency for Space Programs (NIVR). In the framework of past and future X-raymissions the SAX satellite, launched in April 1996, stands out for its very wide spectral coverage from 0.1 to 200 keV, with well-balanced performances of the low-energy and high-energy instrumentation. The sensitivity of the scientific payload will allow the exploitation of the full band of SAX also for weak sources (1/20 of 3C273), opening new perspectives in the study of spectral shape and variability of several classes of objects. In this paper we describe the main aspects of the mission, the instruments, the scientific objectives and operations

The Imager on INTEGRAL

The EIDOS gamma-ray Imager has been proposed in response to the INTEGRAL Announcement of Opportunity issued on the 1st July 1994. Through a combination of different detector technologies, it provides high-quality imaging of celestial gamma-ray sources in the energy range between 20 keV and 10 MeV combined with high continuum sensitivity, high sensitivity to both narrow and broadened gammaray lines and good spectral resolution. The instrument also offers sensitive polarimetry of gamma-ray sources. The scientific objectives of this instrument are vast and range from studies of themost compact Galactic objects through to the structure of the Galaxy and on to active galactic nuclei. Careful attention has been taken to ensure that the design of the EIDOS Imager is compatible with the mission requirement for a Galactic Plane Survey

A study of the X- and gamma-ray emission characteristics of Seyfert 2 galaxies

We have undertaken a study of X- and gamma-ray characteristics of a sample of Seyfert 2 galaxies observed by Ginga. A number of these sources are already included in our catalogue of AGN spectra. We plan to integrate these data at low energy with ROSAT and Einstein data, while at high energy above 50 keV observations have been performed and are planned with the instruments onboard the Compton observatory. The results obtained so far are presented

GRB Observed by IBIS/PICsIT in the MeV Energy Range

We present the preliminary results of a systematic search for GRB and other transients in the publicly available data for the IBIS/PICsIT (0.2-10 MeV) detector on board INTEGRAL. Lightcurves in 2-8 energy bands with time resolution from 1 to 62.5 ms have been collected and an analysis of spectral and temporal characteristics has been performed. This is the nucleus of a forthcoming first catalog of GRB observed by PICsIT.Comment: 6 pages, 3 figures. Poster presented at COSPAR 2008. Advaces in Space Research, accepted for publicatio

In-flight calibrations of IBIS/PICsIT

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. It consists of 4096 independent detection units, ~0.7 cm^2 in cross-section, operating in the energy range between 175 keV and 10 MeV. The intrinsically low signal to noise ratio in the gamma-ray astronomy domain implies very long observations, lasting 10^5-10^6 s. Moreover, the image formation principle on which PICsIT works is that of coded imaging in which the entire detection plane contributes to each decoded sky pixel. For these two main reasons, the monitoring, and possible correction, of the spatial and temporal non-uniformity of pixel performances, expecially in terms of gain and energy resolution, is of paramount importance. The IBIS on-board 22Na calibration source allows the calibration of each pixel at an accuracy of <0.5% by integrating the data from a few revolutions at constant temperature. The two calibration lines, at 511 and 1275 keV, allow also the measurement and monitoring of the PICsIT energy resolution which proves to be very stable at ~19% and ~9% (FWHM) respectively, and consistent with the values expected analytical predictions checked against pre-launch tests.Comment: 5 pages, 7 figures. Accepted for publication on A&A Special Issue on First Science with INTEGRA