Edit: That tutorial also explains that black holes are very simple objects, so the chirps and ringdowns are likewise very simple. So black hole masses can be calculated very precisely. Also, amazingly:
> Just as optical radiation and radio waves, the luminosity of gravitational radiation falls off in inverse proportion to the square of the distance from the source. This makes binary black hole inspirals standard sirens: if we know what the masses of the two black holes are then we can infer the distance to the source by measuring its apparent luminosity. We can precisely measure the masses because the rate at which the frequency and amplitude of an inspiral increases depends only on the masses.
I doubt that the merger was converting all energy into GW. I suppose there might be some effects occurring at such high energy that we don't have precise simulation of what would be emitted.
In any case, that emitted energy certainly wouldn't be good for any living tissue. I don't think you could expect to witness a black hole merger from the comfort of your spaceship a few thousands of miles away.
[0] https://www.astro.cf.ac.uk/research/gravity/tutorial/?page=4...
Edit: That tutorial also explains that black holes are very simple objects, so the chirps and ringdowns are likewise very simple. So black hole masses can be calculated very precisely. Also, amazingly:
> Just as optical radiation and radio waves, the luminosity of gravitational radiation falls off in inverse proportion to the square of the distance from the source. This makes binary black hole inspirals standard sirens: if we know what the masses of the two black holes are then we can infer the distance to the source by measuring its apparent luminosity. We can precisely measure the masses because the rate at which the frequency and amplitude of an inspiral increases depends only on the masses.