Allan Sandage was educated at the University of Illinois and the California Institute of Technology, where he earned his doctorate under Walter Baade. Since 1952 he has been on the staff of the Mt. Wilson and Palomar Observatories, now the Observatories of the Carnegie Institution of Washington, where he began as a graduate student assistant to Edwin P. Hubble. His research has been in stellar astronomy and observational cosmology. With Martin Schwarzschild he determined ages and evolution of globular clusters in order to obtain the ages of the oldest objects known. He has calibrated all of the "standard candles" to determine distances of remote galaxies and has several times presented (often with Gustav Tammann) revised estimates of the value of the Hubble constant. After nearly half a century of observing with the Hale telescope on Palomar Mountain, he now uses the Hubble Space Telescope to determine distances to galaxies using Cepheid variable stars. In the controversy over the value of the Hubble constant, Sandage and Tammann have been vocal proponents of a relatively small value of H₀ implying a relatively large, old universe. Sandage found the first optical counterpart to a radio source that would later be identified as a quasar, and he discovered many more, including the radio–quiet ones. He has published photographic atlases of galaxies. He has received numerous awards, including the Peter Gruber Cosmology Prize, the Tomalla Prize from the Swiss Physical Society, the Crafoord Prize from the Swedish Academy of Sciences, and gold medals from the Royal Astronomical Society, the Astronomical Society of the Pacific, and the Pontifical Academy of Sciences. He has also received the Russell Prize from the American Astronomical Society, the Presidential National Medal of Science, and the Eddington Medal from the Royal Astronomical Society.

Sources:
http://www.phys-astro.sonoma.edu/BruceMedalists/Sandage/
http://www.ociw.edu/research/sandage.html