Distance: 2.4 billion light years = (2.4 * 10^9) * (6 * 10^15) meters = 15 * 10^24 meters away! (approximately) Area of emission sphere at contact with Earth:

Distance: 2.4 billion light years = (2.4 * 10^9) * (6 * 10^15) meters = 15 * 10^24 meters away! (approximately) Area of emission sphere at contact with Earth: 4 * pi * (15 * 10^24 meters)^2 = 2 * 10^50 meters^2 sized sphere when passing Earth (approximately) The amount of energy that must have been spread out over that sphere shaped wave, so any discernible signal reached Earth, much less interacted noticeably with our atmosphere ... simply incredible.