The Astro-2 HUT team was made up of nearly 30 Johns Hopkins and APL scientists and staff. Most of these people were at Marshall Space Flight Center working in shifts around the clock to support the Astro-2 mission. In addition, seven teams of scientists from five institutions around the country were selected by NASA in 1993 to participate with the HUT team in the Astro-2 mission. A number of these "guest investigators" also participated in mission operations in Huntsville.