Skip to main content
Verne M. Willaman Gateway to the Sciences.

Graduate alumnus receives Robert J. Trumpler Award

25 August 2021
Gudmundur Kari Stefansson

Gudmundur Kari Stefansson, who completed his Ph.D. in astronomy at Penn State in 2019, has been honored with the 2020 Robert J. Trumpler Award (presented in 2021) by the Astronomical Society of the Pacific. The award, which is named for a notable Swiss-American astronomer, is presented to a recent recipient of a Ph.D. degree whose research is considered unusually important to astronomy.

Stefansson’s dissertation, “Extreme Precision Photometry and Radial Velocimetry from the Ground,” is described by one of his nominators as “the broadest and deepest demonstration of expertise in precision astronomical instrumentation I have seen.” Another nominator called Stefansson “a multidimensional talent who has demonstrated ability and depth in astronomical instrument hardware, data analysis, and observational astrophysics.” As a testament to the importance of his work, Stefansson was awarded a NASA Earth and Space Science Fellowship, a Leifur Eiríksson Foundation Fellowship, and is currently a Henry Norris Russell Postdoctoral Fellow at Princeton University.  

In his thesis, supervised by Suvrath Mahadevan, professor of astronomy and astrophysics at Penn State, Stefansson characterized and developed a revolutionary innovation—an Engineered Diffuser—for achieving high precision differential photometry from the ground. In differential photometry, the brightness of a star is simultaneously compared to the brightness of other nearby stars, but the atmosphere and limitations inherent in the astronomical detectors used make precise measurements of the brightness of stars exceedingly difficult from the ground. Stefansson’s Engineered Diffuser—a nanofabricated optical device—is capable of molding the image of a star into a broad and stabilized shape on the detector, substantially improving brightness measurements. One nominator called his breakthrough “startling in its simplicity,” adding that “this operational simplicity is very important since it allows widespread adoption.” Currently, Stefansson’s Engineered Diffuser is being used by an increasing number of telescopes around the world to better study extrasolar planets including at the Apache Point Observatory, Penn State’s Davey Lab Observatory, Mt. Palomar Observatory, the Nordic Optical Telescope, and by the Las Cumbres Network.  

The Astronomical Society of the Pacific is an international non-profit scientific and educational organization, founded in 1889, that works to increase understanding and appreciation of astronomy.