Light velocity is186000 using the light velocity when did supernova actually occurred relative to when the Chinese astronomers saw the explosion?

Answer 1

SN185, the first supernova recorded by Chinese astronomers in 185 AD, is estimated to be 8200 lightyears away from us. As such, the actual time of the explosion is estimated to be 8015 BC.

Since large astrometric distances are measured in light years, it is not necessary to know the speed of light or use it in any calculation, for the purposes of answering this question.