The Needle in a Haystack: Combined XMM-Newton and H.E.S.S. Observations of SgrA*

Earlier studies of combined Xray and TeV observations of Sgr A* indicatedevidence for simultaneous activity in the two bands. We propose to observe theobject HESS J1745a??290 which is positionally coincident with the center of ourgalaxy, Sgr A* with XMMNewton and H.E.S.S. for a total of 37.5 hsimultaneously. We search for flares in the Xray band and possible simultaneousactivity in the TeV regime which would pindown the emission mechanisms for theproduction of gamma rays coming from Sgr A*.