HEXTEs

HEXTEs stands for High Energy X-ray Timing Experiment, an instrument on NASA's Rossi X-ray Timing Explorer (RXTE). The HEXTE system comprised two independent detector clusters, commonly referred to as HEXTE A and HEXTE B, designed to perform timing and spectroscopic measurements of hard X-rays from cosmic sources in the approximate range of 15 to 250 keV.

Each cluster contained phoswich scintillation detectors and shared electronics. The two clusters operated in a rocking or dithering mode, alternating between pointing at a target source and a nearby blank field to measure the instrumental and cosmic background. This background subtraction enabled more sensitive measurements of weak signals and improved spectral accuracy when combined with data from RXTE's lower-energy instruments.

HEXTE data supported studies of accreting black holes, neutron stars, X-ray pulsars, and active galactic nuclei, often in conjunction with the PCA instrument to produce broad-band spectra and detailed timing analyses. Data products include spectra, light curves, and background-subtracted count rates, which are archived in the HEASARC and analyzed with standard NASA software packages.

The HEXTE instrument operated from the mid-1990s until the RXTE mission ended in 2012. The two clusters provided complementary sensitivity and redundancy, and their data continue to be used in archival studies and cross-mission comparisons with newer hard X-ray observatories.