HUT's science program for Astro-2 was a combination of expanding on results from Astro-1 and breaking new ground. Seldom in astronomy do observations of one or two objects provide a truly general understanding of a whole class. By observing more active galaxies, elliptical galaxies, cataclysmic variables and nebulae, Astro-2 HUT observations provided a much broader understanding of the phenomena involved in these objects. Also, HUT's improved sensitivity for Astro-2 made it possible to observe objects that were too faint previously, permitting whole new science programs to be pursued.
In addition to new faint targets, there were many brighter UV sources that simply could not be observed in the brief time available on Astro-1. For example, many additional hot white dwarf stars, which are extremely faint in visible light but are actually quite bright in the UV, were observed on Astro-2. These stars represent the cores of burnt-out stars that have lost their outer layers, and as such hold many clues to the end point of the evolution of stars similar to our sun. (Link to Scientific Results from HUT for a description of some Astro-2 findings.)
The Astro-2 flight crew piloted the shuttle and operated the telescopes in orbit.
Bill Blair (email@example.com)