"A candle against the sun" or something like that.

I wonder if the gamma bursts from nuclear testing are discernible from the solar noise? It would reduce the distance to about about 60 light years.

If some ET were looking in our direction, I imagine the radiation signature would look like camera flashes on the far side of a dark stadium where a pyrotechnic performance was occurring on stage.

So long as your eyes are not blinded by the main event, a burst of sparks off to one side might catch your attention - if you are watching during those precious few years when such events happen, and the orientation of all relevant celestial bodies are favorably aligned.

Now, having put it to words, it becomes a hopelessly unlikely signal.