22 Mile Sun Flash - 3"x5" Glass Mirror (Best in Full Screen, HD)

[royrichardsify]

how far can you see this at night?

[ufoengines]

If the flashes were shown through a red filter, do you think that it be easier to see?

[rafowell]

@ufoengines Red flashes stand out more, but filtering greatly reduces brightness, range and detectability. The US tried signal mirror color filters in the 1940s, then dropped the idea. At ranges under a mile, brightness is no problem, so the red might work. Google for "Safe signal mirror" to find retailers for the MPI Safe Signal Mirror: red mirror on one side, plain on the other. I think the plain Coghlan's Survival Signal Mirror (2"x3" glass) is better: the "fireball" aimer is key.