Frederick Sumner Brackett (August 1, 1896 – January 28, 1988), was an American physicist and spectroscopist. Born in Claremont, California, to Frank and Lucretia Brackett, he graduated from Pomona College and worked as an observer at Mount Wilson Observatory until 1920. He observed the infra-red radiation of the Sun. Brackett received a doctorate in physics from the Johns Hopkins University in 1922. Applying a hydrogen filled discharge tube, he discovered the hydrogen Brackett series, where an electron jumps up from or drops down to the fourth fundamental level, in 1922.