  The Haystack Telescope is an antenna with a diameter of 37~m and an
elevation-dependent surface accuracy of $\le{}100~\mu{}\rm{}m$ that is capable
of millimeter-wave observations. The radome-enclosed instrument serves as a
radar sensor for space situational awareness, with about one-third of the time
available for research by MIT Haystack Observatory. Ongoing testing with the
K-band (18-26~GHz) and W-band receivers (currently 85-93~GHz) is preparing the
inclusion of the telescope into the Event Horizon Telescope (EHT) array and the
use as a single-dish research telescope. Given its geographic location, the
addition of the Haystack Telescope to current and future versions of the EHT
array would substantially improve the image quality.
