This is an image of the instrument called the Proportional Counter Array on the Rossi X-ray Timing Explorer (RXTE) satellite.
X-ray astronomy detectors have been designed and configured primarily for energy and occasionally for wave-length detection using a variety of techniques usually limited to the technology of the time.
X-ray detectors collect individual X-rays (photons of X-ray electromagnetic radiation) including the number of photons collected (intensity), the energy (0.12 to 120 keV) of the photons collected, wavelength (~0.008 to 8 nm), or how fast the photons are detected (counts per hour), to tell us about the object that is emitting them.
