[DungeonMaster]

But how is all these determined from strictly telescopic observance or is some data taken from space EM waves?

Well one thing I can say with confidence is that everything we know about black-holes, with the possible exception of a bit of data from this article, is from our observation of EMR and not the observation of gravity waves

[wardaddy]

I didn’t mean to infer gravity waves..did I say that..sorry if I did.

I’m asking to be educated how do we learn about black holes given their distance and unusual nature

Is it telescopic observance and interpreting electromagnetic radiation only?

Do we get most of this from special orbiting scopes...infrared etc

Does anyone know how many light years out we can make calculations about the properties of what we’re looking at