Hard X-ray images of the galactic centre

The centre of our Galaxy has been observed extensively at infrared and radio wavelengths. The compact radio source at the nucleus (Sgr A^*) may be a weaker form of those in active galaxies. The region is obscured in the visible band by ~30 magnitudes of absorption but the intervening dust and gas clouds become transparent again for X-rays of energy greater than a few keV. We report here observations made with a coded mask X-ray telescope flown on the Spacelab 2 mission (29 July to 6 August 1985), yielding for the first time images of the galactic centre in high-energy X-rays up to 30 keV. Components detected include a region of diffuse emission 2° in diameter and several new point sources. At the higher energies emission from the nucleus is weak and the region is dominated by one of the surrounding point sources.