Harold C. Simmons Dark Energy Optical System Installed on HET

The Harold C. Simmons Dark Energy Optical System is a complex set of optics, including four mirrors, that sit above the primary mirror of the Hobby-Eberly Telescope on a support structure called a tracker. The primary mirror feeds light from cosmic targets into the Simmons System, which sharpens the view before sending that light into the telescope's science instruments. (Ethan Tweedie Photography)