I want to clarify: I chose "two minutes" as a totally arbitrary example. I think we are all clear about that -- but just "Duration X", for some value. Importan

I want to clarify: I chose "two minutes" as a totally arbitrary example. I think we are all clear about that -- but just "Duration X", for some value. Important to note another class of very violent, energetic event that can emit gamma rays is an ultra-hot accretion disk around a galaxy core black hole. Something larger than our solar system... Such systems can exhibit changes in brightness, but generally we see that over much larger scale. Something smaller than a galaxy, like a star, could change brightness much more rapidly.