The enigmatic neutron star X-ray binary AX J1754.2-2754

We propose a single 35 ksec XMMNewton observation of the veryfaint Xraybinary AX J1754.22754, an enigmatic neutron star system that is underluminousby orders of magnitude compared to the wellknown bright sources. AXJ1754.22754 is a candidate ultracompact Xray binary and observations withother Xray satellites suggest that it has an unusually soft spectrum with apowerlaw index of virgul3. With our proposed observation we will obtain highqualitydata of AX J1754.22754, which allows for a detailed spectral (e.g., verify itssoftness) and timing study (e.g., search for possible orbital modulations, Xraypulsations and typeI Xray bursts), which can refine our understanding of thenature of this system. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]