THE ROSSI X-RAY TIMING EXPLORER

RXTE has been operating for nearly 2 years and is planning the third. The spacecraft performance has been good and the three instruments are operating well. Observations have been made of the range of targets s uitable for RXTE, including such different objects as accreting neutro n stars and black holes, stellar flares, and supernova remnants. The g oals of studying high time resolution and broad energy range and optim ising multiwavelength participation are yielding important results. Os cillations found from low-mass X-ray binaries probably are signatures of the spin of the neutron stars and of the shortest orbital periods a round the neutron stars. These are constraining neutron star parameter s. Oscillation and spectral results from black hole candidates bring i nto the realm of possibility the possibilities of measuring the spins of the black holes and using X-ray data to test predictions of gravita tion theory. Multiwavelength observations are leading to identificatio n of the locations of the X-ray emission regions and, in the case of t he microquasars, to understanding of the mechanisms for jet formation. Recently faster observing response than originally planned has made p ossible some RXTE contributions to identification of gamma-ray bursts.