Guardians of the Sky
The glass plates collection at the CfA serves as a record of skies around the world across more than a century.
It was 16 degrees on a January night, the cold made worse by the fatigue of working so many hours. Box after box, heavy with glass, had to pass through the basement window, into the snow-covered parking lot.
But if the cold made for deep discomfort — and chattering teeth — it also proved a disaster-recovery ally after a water-main break flooded the Harvard College Observatory's Plate Stacks, a unique historical treasure holding hundreds of thousands of glass plate negatives that serve as a record of skies around the world across more than a century.
By the time the flooding was discovered, early on Martin Luther King Jr. Day, the lowest level of the three-story stacks had been flooded to three feet, immersing 61,000 of the negatives and derailing the Digital Access to a Sky Century at Harvard (DASCH) project, a decade-long scanning effort aimed at making the plates more accessible for study.
The flood also soaked the custom-built digital scanner at the heart of the project. But the plates themselves were the main concern. With those in good repair, everything else would be OK.
"This collection is unparalleled, in my opinion," said Brenda Bernier, who is the James Needham Chief Conservator and head of Harvard Library's Weissman Preservation Center and Collections Care. "It's the depth and breadth of the data, it's extraordinary. The scale — hundreds of thousands of one of the most vulnerable formats."
Bernier credited the Harvard Library Collections Emergency Team and photograph conservators Erin Murphy and Elena Bulat with understanding that the chill could aid the rescue effort. With the plates stored in soaked paper sleeves, the biggest danger to the photographic emulsion was mold. Mold spots would mar a record that consists of thousands or even many tens of thousands of pinpoints of light. The best course, the team decided, was to get the plates into the sub-freezing air as quickly as possible.
Since that night, the plates have been kept safely frozen and the mold at bay. They were transferred into refrigerated trailers, which are now stored with a North Andover company that specializes in document recovery. Early tests have suggested the photographic emulsion that coats one side of each plate will survive unaltered.
Conservators are working with Jonathan Grindlay, the Robert Treat Paine Professor of Practical Astronomy, and others at the Harvard-Smithsonian Center for Astrophysics (CfA) to devise a process for restoring the plates. These will include extracting them from the paper sleeves, which have to be photographed because they include data critical to interpreting the images, and then cleaning them of silt and grime. The methods devised at the Weissman Preservation Center, Bernier said, will be taught to technicians at Polygon in North Andover, who will carry out the restoration work, which is expected to take a year and a half.
Grindlay, who heads the DASCH project, and CfA director Charles Alcock expressed deep appreciation for both the tireless efforts of staff members and the expertise of the Harvard Library team.
Read more at the Harvard Gazette...