Yeah, it is kinda tough to see, and it doesn't really catch your eye.
I'd like it if it kinda pulsed/faded between black and white continuously (not like an outright strobe -- just a gentle, fading pulse with a period of 1-2 seconds). The white would help it stand out against dark/nighttime backgrounds, while the black would help it stand out against bright/daytime backgrounds. The fading would help it to catch your eyes in spite of any busyness on screen.
In addition, I think it would be cool to have an indicator icon pop-up on the edge of your screen when a fellow crewman or allied crewman spots an enemy ship that's out of your FoV. (Obviously it would be replaced with the normal box indicator when it comes into view.) Of course, I can understand if this would be a little much for some people and would be fine with not having it.