Holder points out that when a gamma ray hits the atmosphere, it produces a small flash of blue light that lasts only a few billionths of a second. The VERITAS cameras take 200 photographs a second. He and his team developed software that would sift out the gamma rays from all of the background noise, representing about one-tenth of the images.
"Our software throws away all the stuff that isn't gamma rays," he says.
Holder says that he and his colleagues will keep observing the Crab Pulsar for the next few years, as the spinning star continues to wind down.
With so much radioactivity being spun out, are there any implications for us here on Earth? As Holder notes, gamma rays are ever-present in the universe, and fortunately Earth's atmosphere protects us from them.
Currently, Holder and his group at UD are in the middle of building 2,000 photo detectors for the new cameras for the VERITAS telescopes.
"The new photodetectors collect 50 percent more light than our existing ones, which will make us more sensitive to gamma rays, particularly in the energy range where the Crab Pulsar emits," Holder notes.
VERITAS is funded by the U.S. National Science Foundation, U.S. Department of Energy Office of Science, Smithsonian Institution, Natural Sciences and Engineering Research Council of Canada, Science Foundation Ireland, and Science and Technology Facilities Council of the United Kingdom.
The Bartol Research Institute is a research center in UD's Department of Physics and Astronomy. The institute's primary function is to carry out forefront scientific research with a primary focus on physics, astronomy, and space sciences.