The object, dubbed FIRST J1419+3940, is in the outskirts of a galaxy more than 280 million light-years from Earth. Astronomers calculated that the explosion and burst of gamma rays should have been seen sometime in 1992 or 1993
VLASS (VLA Sky Survey) is the biggest observing project for VLA. Started in 2017, the survey will use 5,500 hours of detecting time over seven years. The survey will make three thorough scans of the sky visible from the VLA, roughly 80 percent of the sky. Initial images from the first round of observations now are available to astronomers.
The astronomers noted that an object that appeared in images from a previous VLA survey in 1994 did not appear in the VLASS images. They then searched for supplementary data from the VLA and further radio telescopes. They found that observations of the object's position in the sky dating back as far as 1975 had not detected it until it first appeared in a VLA image from 1993. The object then appeared in numerous images made with the VLA and the Westerbork telescope in the Netherlands from 1993 through 2015.