Harvard researchers are building a celestial time machine that lets astronomers look back at hundreds of thousands of objects in the Earth’s skies over the past century.

The effort aims to digitize 525,000 glass photographic plates taken at observing sites around the world between the 1880s and the 1980s. The collection, the largest such in the world, contains a treasure trove of largely unexamined data, according to Paine Professor of Practical Astronomy Jonathan Grindlay, who is leading the digitizing effort.

Photo Kris Snibbe/Harvard University News Office

Grindlay said each of the plates has been examined for one or a few objects of interest to specific astronomers. When one considers that each plate holds images of upwards of 100,000 objects and that each visible object has been photographed between 50 and 3,000 times over the years, the potential knowledge about the changing universe hidden in the Harvard College Observatory plate stacks is enormous.

“DASCH will look at every object on the plate with specially developed software and measure its brightness. You can not know what you’re looking for and still find something,” Grindlay said. “We’re part of a wave that is looking at the sky for its variable objects, for everything that goes bump in the night — and that turns out to be a lot. DASCH will open a new window for time domain astronomy.”

The digitizing effort, called DASCH for Digital Access to a Sky Century @ Harvard, got under way in 2004 when it received funding from the National Science Foundation. After two years spent on the development of a custom-made scanner for the plates and an initial version of the scanning software, the first scans began in 2006. Since then, work has focused on crafting software to make sense of the enormous amount of data the plates hold.

Alvin Powell
Harvard News Office