Onward and Backward

Back in the days of my youth, optical astronomy was done with telescopes, and the sky recorded on dry glass plates.  Starting in the 1890s, millions of glass plates were viewed, then stored in archives throughout the world.  They’ve been largely ignored in the years since— there are so many, where do you start?  Yet it’s a scientific archive filled with undiscovered treasures.

But lately a team from the University of Chicago and and the Kavali Institute has been scanning and digitizing the old plates, using off-the-shelf equipment, and finding a few things the original viewers missed.

“After we select a plate, we make sure the surface is clean so that dust particles don’t get mistaken for stars in the final image. Then, we set our scanner to the highest quality we can and produce an image file. In effect, we are considering the scanner to be a scientific instrument: for each small piece of information on the plate, we get a digital rendition of the amount of light transmitted through the photograph. From there, we upload the resulting file to a website which maps the celestial coordinates onto the image, which also creates a file in a standardized format for astronomical analysis.”  

. . . “The simplicity of the process makes it possible to digitize a large number of plates in a relatively small amount of time.  It also has the benefit of not requiring a custom scanner, making it accessible to teams without the wherewithal to design or purchase one. Custom scanners are prohibitively expensive. If our methods can be generalized, then photographic plate collections from multiple observatories could be rendered available for use in scientific research.”

One of the first plates scanned turned up a possible supernova occurring in 1903 in the constellation Pegasus.

When astronomers noticed an anomalous dimming seen in Tabby’s Star KIC 8462852, they looked at old glass plates of the same region to show that the strange star is actually fading over longer time scales. Another study looked at the nearby white dwarf named Van Maanen’s Star and demonstrated that astronomers had potentially documented evidence for exoplanets waaaay back in 1917… had they known to look for it.

Forward in science . . . by revisiting the past!  Onward and backward!

[via Janice Gelb]