Journal ArticleThe Haystack Telescope as an Astronomical InstrumentKauffmann, Jens; Rajagopalan, Ganesh; Akiyama, Kazunori; Fish, Vincent; Lonsdale, Colin; Matthews, Lynn D.; Pillai, Thushara G.S.The Haystack Telescope is an antenna with a diameter of 37 m and an elevation-dependent surface accuracy of ≤100μm 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.2023-02-0110436894Galaxies11192075-4434https://doi.org/10.3390/galaxies110100092309542; 2108989; 1935980; 2309536National Science Foundation