XMM observations of HESSJ1804-216: a clue to the PSR1800-21:G8.7-0.1 association

The TeV instrument H.E.S.S. discovered during a survey of the Galactic planethree sources close to highly energetic pulsars. It was hence suggested thatthese gammaray sources are counterparts of pulsar wind nebulae (PWN). Indeed,in one of these cases the PWN has been well studied with XMMNewton, whichallowed a firm identification of the TeV source with the PWN. With thisproposal, we want to use XMMNewton to identify the Xray counterpart of HESSJ1804216. This TeV source can also most likely be explained as emission from aPWN, but so far this PWN around PSR B180021 has not been detected in any otherwaveband. The PWN detection may also hold the clue for the so far not firmlyestablished association of PSR B180021 to the supernova remnant G8.70.1. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]