P. Laurent

SIGMA: The hard X-ray and soft gamma-ray telescope on board the GRANAT space observatory

Abstract 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.

INTEGRAL upper limits on gamma-ray emission associated with the gravitational wave event GW150914

Using observations of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), we place upper limits on the gamma-ray and hard X-ray prompt emission associated with the gravitational wave event GW150914, which was discovered by the LIGO/Virgo Collaboration. The omnidirectional view of the INTEGRAL/SPI-ACS has allowed us to constrain the fraction of energy emitted in the hard X-ray electromagnetic component for the full high-probability sky region of LIGO triggers. Our upper limits on the hard X-ray fluence at the time of the event range from

SIGMA detection of hard X-ray emission from the soft transient type I X-ray burster KS 1731-260

{F}_{gamma }=2times {10}^{-8}

Three years of monitoring GRS 1758-258 : an extremely hard X-ray source near GX 5-1

erg cm(−)(2) to

Discovery with the Sigma telescope of hard X-rays from the globular cluster Terzan 2

{F}_{gamma }={10}^{-6}

SIGMA/GRANAT Discovery of GRS 1739–278, A Hard X-Ray Transient in the Galactic Bulge

erg cm(−)(2) in the 75 keV–2 MeV energy range for typical spectral models. Our results constrain the ratio of the energy promptly released in gamma-rays in the direction of the observer to the gravitational wave energy E

SIGMA observation of hard X-ray emission from the ultrasoft X-ray transient Triangulum Australe X-1 (A1524 - 62)

{}_{gamma }/

On the hard X-ray variability of Centaurus A

E

Sigma hard X-ray observations of GX 339-4 during the hard state and a transition to the soft state

{}_{mathrm{GW}}lt {10}^{-6}

The first soft gamma-ray image of the Galactic Centre with arc-min accuracy

. We discuss the implication of gamma-ray limits for the characteristics of the gravitational wave source, based on the available predictions for prompt electromagnetic emission.