The Soft X-ray Telescope
The soft X-ray telescope (SXT) provides, for the first time, the opportunity to image the Sun in X-rays over a long period of time with both high temporal and spatial resolution. It gives Yohkoh and important capability for solar science beyond the study of flares, the primary objective of the mission. The SXT instrument was jointly developed by the Lockheed Palo Alto Research Laboratory and the National Astronomical Observatory of Japan. Collaborators include the University of Tokyo, Stanford University, the University of California at Berkeley, and the University of Hawaii.

The SXT instrument that makes the observations in support of our scientific objectives is a glancing incidence telescope of 1.54 m focal length which forms X-ray images in the 0.25 to 4.0 keV range on a 1024x1024 virtual phase CCD detector. A selection of thin metallic filters located near the focal plane provides the capability to separate the different X-ray energies for plasma temperature diagnostics. Knowledge of the location of X-ray images with respect to features observable in visible light is provided by a coaxially mounted visible-light telescope which forms its image on the CCD detector when the thin metallic filter is replaced by an appropriate glass filter.

SXT Optics (click to enlarge)
 SXT Assembly (click to enlarge)