It should be clear by now that I've measured and mapped radiation events of several kinds for 40 odd years.

It's clear that you're suggesting there might be some novel as yet unknown way to detect and location pinpoint a coin sized industrial Cs-137 source used in a mining radiation gauge from the distance of a low orbit (?) satellite.

I'm open to hearing how exactly this might be achieved, I'm sure the other person in this parallel discussion would also have an interest, as they stated they're working at a US national lab in precisely this area.

If you turn to that discussion they've addressed the measured and known way in which the gamma radiation falls off with distance .. although they didn't address how that also falls off with air column mass (air pressure, tempreture, water vapor level (humidity)) etc. and determined this is possible to detect in a one second window from 40 metre distance.

It also rather rules out using direct gamma detection of such a weak source from 25km through the full mass of the atmosphere so, again, it'd be nice to have a concrete indication from you of what it might useful to look for.

Concrete, mind, and not more of this handwavy Sir Kenelm Digby Powder of Sympathy [1] remote sensing magic.

[1] https://en.wikipedia.org/wiki/Powder_of_sympathy