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The cosmic incident, which happened 130 million years ago in a nearby galaxy called NGC 4993, is the source of the gravitational wave detected by LIGO and VIRGO in August this year.
This historic event was observed by a network of observatories from across the world, including the Dark Energy Camera, the primary observing tool of the Dark Energy Survey (DES), mounted on the 4-meter Blanco telescope in Chile.
Dr Eduardo Balbinot, Research Fellow from the University of Surrey and member of the DES team, was observing when the LIGO source was first spotted. He said:
“This was a once in a lifetime opportunity. We were given the task of watching NGC 4993 repeatedly, which was a challenge because it was setting less than one hour after dark. This made each and every day a race against time. Every second had to be carefully planned so no precious telescope time was wasted.
“When the LIGO team gave us details of what we were looking for, a neutron star merger, I was extremely excited. Luckily we had good weather and were able to detect the LIGO source.”
The event, hopefully the first of many, provides a new and unique way to measure the present expansion rate of the universe. Just as astrophysicists use type Ia supernovae as “standard candles” (objects of a known intrinsic brightness) to measure cosmic expansion, kilonova can be used as “standard sirens” (objects of known gravitational wave strength).