Keywords: Ab30 rgb1.jpg en Abell 30 at the prime focus of the 4-meter Mayall telescope at Kitt Peak National Observatory Red Hydrogen alpha; Green O III 5007; Blue 6100 Angstrom continuum just shows the stars Stars look white because they show up in all three filters Logarithmic scaling http //violet pha jhu edu/~wpb/abell30/ab30 html http //violet pha jhu edu/~wpb/abell30/ab30_rgb1 jpg William P Blair http //violet pha jhu edu/~wpb/abell30/ab30 html William P Blair PN A66 30 Kitt Peak National Observatory Images Logarithmic intensity scale |