announced a supernova that exploded 10 billion years ago and that was estimated to be 18 billion light years away.
Is it 18 giga-lightyears away now, or was it 18 giga-lightyears away when it exploded?
It would make more sense to me if it was an estimate of the current distance. An estimate of the distance seen, instead, would be more directly based on the red-shift. I think they should give both distances, to make it clear.
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