It is located in zone 33:50, down south on the coast directly west of The Glow, and is highly Radiated. It is usually raining radioactive rain in this location, and everyone who goes there is affected, even if you hide inside a building. Its radiation only applies to those who enter, and does not affect anyone lurking over it on the world map.
Dayglow has two entrances, so use the Preview function if you want to enter south.
NOTE: Remember! This is a full loot-drop PvP location, so unlike the rest of The World, when you fail here in combat, your Items are all left behind in a pile on the ground. Anyone else there can steal it, and looters will exploit this.
This location is being monitored by developers who are likely expanding the location for future updates, and even now the Slags are being moved around to slow down players from farming the place.
Dayglow is guarded by 4 very tough Slags, similar to Warehouse. All Slags have 480+ HP, high Critical Chance and crit resists, DR and all possible Perks, including Support Perks. One Slag is a female armed with a Needler Pistol, and two male Slags are armed with H&K CAWS. The boss Slag is the toughest with 552 HP. He wields a Minigun and will take you down very quickly unless you have a strong plan, the right Drugs including Psycho and Beer, and some backup.
It varies in intensity based on the rain. Sometimes the rain is light, and you can stand inside Dayglow for an hour and barely be affected as long as you use Rad-X and RadAway diligently. At other times the rain is heavier and you just burn worse and worse no matter what you do, and you'll need to exit more often to keep your rads under 11%. Remember, when your radiation gets over 10%, you lose a SPECIAL point. If your Agility decreases, you're slower in combat. When your rads go over 20%, you lose another point of SPECIAL. Your ability to fight will decrease as your rads increase in 10% increments, until you melt into a puddle of goo on the ground, or get out of there. You should get Snakeater before going in, and go pay an NPC doctor in Hub or Junktown when your rads are over 10%.
The Loot Locker
The box closes on its own on a variable timer, and sometimes loot will appear inside of it, and sometimes not, so it's often empty. The timer varies usually inside of 10 minutes, and sometimes it closes maybe 1 minute after you checked it last. It's best to get a team and go try to figure it out yourselves.
Loot here includes Power Armor and even Advanced Power Armor, special varieties of Combat Armor, and rarely-seen weapons like Laser Support Weapons, Bozars, YK42B Pulse Rifles, Vindicator Miniguns, Gauss Rifles, Gauss Pistols, Solar Scorchers, XL70E3 assault rifles, Pancor Jackhammer shotguns, implant modules, rare combat helmets, and more.
You can close the locker when you check it, but that doesn't affect loot generation. This is why most players prefer to leave it open when they check it, and let it close on its own, which serves as their prompt to go check it again.