On the brilliant site She Is An Astronomer. http://www.sheisanastronomer.org/index.php/history/cecilia-payne-gaposchkin
She became the first person to earn a PhD in astronomy from Radcliffe for her thesis “Stellar Atmospheres, A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars”. Astronomer Otto Struve characterized it as “undoubtedly the most brilliant Ph.D. thesis ever written in astronomy”.
Payne-Gaposchkin’s PhD is considered by many as the turning point of the Harvard College Observatory, and of women in astronomy, allowing women to enter the mainstream world of astronomy. She received the Annie Cannon Award in astronomy in 1934 for her work.