0420102

We propose a 400 ksec INTEGRAL observation of the dipping low-mass X-ray binary (LMXB) 4U 1254-690 simultaneous with an accepted (priority A) 60 ksec XMM-Newton AO-5 obseravtion. Te 0.5-10 keV spectroscopy provided by XMM-Newton will be strongly enhanced by the INTEGRAL observation which will allow the continuum to be characterized to an expected energy of 300~keV. The changes in the 0.5--10 keV continuum and the H- and He- like Fe K absorption features around 6.5 keV during dips have been successfully modeledby changes in the column density and ionization state of a highly photo-ionized absorber (Boirin et al. 2005 Diaz Trigo et al. 2006). However to accurately characterize the ionization state of the absorber it is necessary to know the overall level of the continuum above 10 keV since this is where the bulk of the ionizingphotons are. These previous studies used non-contemporaneous BeppoSAX and R-XTE observations to estimate the power-law index of the high-energy continuum which introduces large uncertainties intheir estimates of the ionization parameter. The INTEGRAL observation proposed here in conjunction with the alreadyapproved XMM-Newton observation will provide for important new insights into the nature of photo-ionized plasmas in LMXB. [truncated! Please see actual data for full text]