In‐Flight Performance of the High Energy X‐Ray Timing Experiment on the<i>Rossi X</i>‐<i>Ray Timing Explorer</i>

Abstract

The High Energy X-Ray Timing Experiment (HEXTE) is one of three scientic instruments aboard the Rossi X-Ray T iming Explorer (RXT E), which was launched on 1995 December 30. RXT E performs timing and spectral studies of bright X-ray sources to determine the physical parameters of these systems. The HEXTE consists of two independent clusters of detectors, each cluster containing four NaI(Tl)/CsI(Na) phoswich scintillation counters sharing a common 1 FWHM eld of view. The eld of view of each cluster is switched on and o source to provide near real-time background measurements. The net open area of the eight detectors is 1600 cm2, and each detector covers the energy range 15250 keV with an average energy resolution of 15.4% at 60 keV. The in-ight performance of the HEXTE is described, the light curve and spectrum of the Crab Nebula/pulsar is given, and the 15240 keV spectrum of the weak source, active galaxy MCG ]8-11-11 is presented to demonstrate the weak source spectral capabilities of HEXTE.