Discovery of a New X-Ray Filled Radio Supernova Remnant around the Pulsar Wind Nebula in 3EG J1809–2328

We report the discovery of a partial [image]2 degree diameter nonthermal radio shell coincident with Taz, the pulsar wind nebula (PWN) in the error box of the apparently variable -ray source 3EG J1809-2328. We propose that this radio shell is a newly identified supernova remnant (SNR G7.5-1.7) associated with the PWN. The SNR surrounds an amorphous region of thermal X-rays detected in archival ROSAT and ASCA observations, putting this system in the mixed-morphology class of supernova remnants. G7.5-1.7 is the fifth such supernova remnant coincident with a bright GeV source, and the fourth containing a pulsar wind nebulae.