I'm unsure, but it could just be an unconventionally shaped chimney. It does kind of look like a Red Arrow, but I don't really see a mount or a pole. I was looking at it closer, and it seems too tall to be a Decot. If it is a siren, judging by its overall shape and height, it may possibly be a Cosg...
I'll play. Here's some stuff from Atlanta from various points in the mid-1960s. https://media.discordapp.net/attachments/688869656622006363/832118024181907467/rYsjswwXuJwAAAABJRU5ErkJggg.png?width=1424&height=708 https://media.discordapp.net/attachments/688869656622006363/994690251211685998/unkn...