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XSSJ1227.0-4859 is a peculiar, hard X-ray source recently positionallyassociated to the Fermi-LAT source 1FGLJ1227.9-4852/2FGLJ1227.7-4853.Multi-wavelength observations have added information on this source, indicatinga low-luminosity low-mass X-ray binary (LMXB), but its nature is still unclear.To progress in our understanding, we present new X-ray data from a monitoringcampaign performed in 2011 with the XMM-Newton, RXTE, and Swift satellites andcombine them with new gamma-ray data from the Fermi and AGILE satellites. Wecomplement the study with simultaneous near-UV photometry from XMM-Newton andwith previous UV/optical and near-IR data. The X-ray history of XSSJ1227.0-4859over 7yr shows a persistent and rather stable low-luminosity (~6x10^33d_{1\,kpc}^2 erg/s) source, with flares and dips being peculiar and permanentcharacteristics. The associated Fermi-LAT source 2FGLJ1227.7-4853 is alsostable over an overlapping period of 4.7\,yr. Searches for X-ray fastpulsations down to msec give upper limits to pulse fractional amplitudes of15-25% that do not rule out a fast spinning pulsar. The combinedUV/optical/near-IR spectrum reveals a hot component at ~13\,kK and a cool oneat ~4.6\,kK. The latter would suggest a late-type K2-K5 companion star, adistance range of1.4--3.6kpc and an orbital period of 7--9 h. A near-UVvariability (>6\,h) also suggests a longer orbital period than previouslyestimated. The analysis shows that the X-ray and UV/optical/near-IR emissionsare more compatible with an accretion-powered compact object than with arotational powered pulsar. The X-ray to UV bolometric luminosity ratio could beconsistent with a binary hosting a neutron star, but the uncertainties in theradio data may also allow an LMXB black hole with a compact jet. In this caseit would be the first associated with a high-energy gamma-ray source.

X-ray follow-ups of XSSJ12270-4859: a low-mass X-ray binary with gamma ray FERMI-LAT association