2. The High Energy X-Ray Timing Experiment

The High Energy X-Ray Timing Experiment (HEXTE) consists of two clusters of phoswich scintillation detectors (see Section 2.1). Background subtraction is done by rocking on and off the source. The two clusters are pivoted so that they rock perpendicular to each other. The detectors dwell on the source for 16 s. It takes 2 s to move to the background field and 2 s to move back. Thus the background dwell time is 12 s. The background pointing offset can be set to $\pm$3^$\prime$ or $\pm$1.5^$\prime$. HEXTE's energy resolution is about 17% at 60 keV (1998). Both HEXTE and the PCA have a circular field of view with a FWHM of 1^$\prime$.