Changed back to original circle marker, it now uses the color of your Arma 3 UI. Set this in the game options. And it is larger and easier to see. This is just like the ACE3 tactical ping. This is a good compromise. I tried some graphics from the Internet, but they were so transparent for some reason, they were invisible.

Updated with a nice proper icon.

Changed icon per request.

Changed icon from red to yellow.

Changed icon.