HartRAO Visitor Centre is the public gateway to the South African Radio Astronomy Observatory’s Hartebeesthoek site, a national research facility in the hills northwest of Johannesburg. Exhibits and guided programmes explain radio astronomy, space geodesy, very-long-baseline interferometry and the observatory’s role in satellite tracking, telemetry, communications and navigation. During scheduled programmes visitors can see the 26-metre radio telescope and other scientific instruments and meet the people who operate them; open days add public access to the working site. HartRAO shares an entrance area with SANSA Space Operations but is a distinct observatory and visitor experience. All visits must be booked in advance through the science-awareness team, and open-day, group and instrument access vary with the research programme. Address: Farm 502 JQ, Hartebeesthoek, Broederstroom Road R400, Krugersdorp District, Gauteng, South Africa.