American Association of Variable Star Observers
As a boy, Houston learned to build microscopes and telescopes and developed an interest in amateur astronomy. He soon observed all 103 nebulae and star clusters in the Messier catalog. While at the University of Wisconsin he began observing variable stars and in 1931 he joined the American Association of Variable Star Observers (AAVSO). Eventually, he contributed more than 12,000 variable star observations to AAVSO.