Localising the HESS galactic centre point source

Abstract

Observations by the H.E.S.S. system of imaging atmospheric Cherenkov telescopes provide the most sensitive measurement of the Galactic Center region in the energy range 150 GeV - 30 TeV. The vicinity of the kinetic centre of our galaxy harbours numerous objects which could potentially accelerate particles to very high energies (VHE, > 100 GeV) and thus produce the γ-ray flux observed. The centroid of the point-like emission measured by H.E.S.S. was found to be in good agreement with the position of the supermassive black hole Sgr A* and the recently discovered PWN candidate G359.95-0.04. Given a systematic pointing error of about 30", a possible association with the SNR Sgr A East could not be ruled out with 2004 H.E.S.S. data. In this contribution an update is given on the position of the H.E.S.S. Galactic Centre source using 2005/2006 data. The systematic pointing error is reduced to 6″ per axis using guiding telescopes for pointing corrections, making it possible to exclude with high significance Sgr A East as the source of the VHE γ-rays.