Some hardware options for an X-ray timing explorer

The objectives and potential capabilities of an X-ray timing mission are discussed, along with some hardware options. Some of the possible uses of such an instrument are outlined, including the investigation of X-ray bursts, flares and pulsars, possible black holes, erratic variables, steady accretion and active galactic nuclei. While the basic detector can be described as a 1 sq m array of proportional counters with an energy response of 2-15 keV, the pros and cons of various options for improving the hardware are presented. These include increasing the bandwidth, using a smaller or larger area, and the capability for microsecond timing, all-sky monitoring, and flexible pointing; costs are also considered.