The RXTE had three instruments — an All-Sky Monitor, the High-Energy X-ray Timing Experiment (HEXTE) and the Proportional Counter Array.

This, together with 1 GB (approximately four orbits) of on-board solid-state data storage, give added flexibility in scheduling observations.

[5] The ASM consisted of three wide-angle shadow cameras equipped with proportional counters with a total collecting area of 90 cm2 (14 sq in).

Each cluster could "rock" (beam switch) along mutually orthogonal directions to provide background measurements 1.5° or 3.0° away from the source every 16 to 128 seconds.

The instrumental properties were:[11] The PCA is being built by the Laboratory for High Energy Astrophysics (LHEA) at Goddard Space Flight Center.

[11] Observations from the Rossi X-ray Timing Explorer have been used as evidence for the existence of the frame-dragging effect predicted by the theory of general relativity of Einstein.

[12] In February 2006, data from RXTE was used to prove that the diffuse background X-ray glow in our galaxy comes from innumerable, previously undetected white dwarfs and from other stars' coronae.