Pismis 20 is a compact open cluster in Circinus. It is located at the heart of the Circinus OB1 association in the Norma Arm of the Milky Way Galaxy. Pismis 20 is about 3,270 pc away and only about 5 million years old. HD 134959, a blue supergiant variable star also called CX Circinus, is the brightest star in Pismis 20.