0320093

We propose INTEGRAL observations of two bright low mass X-ray binariesGX 17+2 and GX 13+1 with an exposuretime of 300 ks. These observations will be part ofa campaign of coordinated multiwavelength observationsin the radio optical/IR X-ray and$gamma$-ray bands. This project is specifically aimed at studyingthe recently discovered hard power-law tails in luminous Z sourcesand their correlation with ``inferred mass accretion rate(as defined by the position on the X-ray color--color diagram) andother source properties.These high-energy tails seem to be present (or more prominent) at low inferredaccretion rates i.e. at periods of maximum radio emission from thesesources. We plan to directly probe this correlation between radio emission(probably due to jets) and hard tails which might indicate jets as theorigin of hard components in luminous Z sources.This proposal was already accepted in the INTEGRAL AO2 in B priority however the observation could not be performed. [truncated! Please see actual data for full text]