Unidentified technology - BLACKHAWK DOWN

I saw Blackhawk Down for the first time the other day and I couldn't identify a piece of equipment.
In a scene at night a soldier has to throw a grenade looking device on top of the roof to mark where the bad guys are. This device doesn't explode but somehow lights up the enemy for helicopter pilots wearing night vision. It isn't a flare or anything like that and it seems to only light up the bad guys as glowing green.
So does anyone know what it might be ?

its an infra-red flare, it emits lights at certain frequencies like a normal flare would do so. They use it so that the Hcopter pilots would see it and not the skeletons

Case closed

Not to disagree Necro, but wouldnt a flare emit super bright light from a central source? There isnt a bright point from this flare (that I remember, or if so, it isnt super bright), it simply highlights the guys around it. Is this done via the frequencies used.

(Normally a flare would create a bright spot in night vision goggles stopping the user form viewing anything at this point, this one seems a lot "softer")

flash bomb?

only saw the film once when but when he chucked the thing on the roof it started to flash so the heli could see it and pick it up on night vision ill be able to tell you more when i buy it on dvd comes out on monday

The object he threw on the roof was an infrared strobe light. The strobe didn't light the place up or make the guyís green, what you saw was the night vision the pilots were using. You wouldn't be able to see the strobe without wearing the night vision goggles. The reason he threw it was to mark the enemy's position so the AH/MH-6 "Little Birds" could come in for a gun erupt.