Main light switch: extremely bright (long press the main light switch to turn on, release to turn off). People may use flashing blue lights to mark a location, to highlight a vehicle, or even as a part of taking photographs. Caveats are when being escorted by a police car also showing blue lights, or within the local police force area where an animal ambulance company has signed a Memorandum of Understanding with its chosen local police force to be able to show a blue light. Police cars, fire engines and ambulances are the obvious examples that most people will be aware of. You can even use Color Flashlight to display your own personal message by typing in text, or host your own personal dance party with the built-in strobe light.

Electricity firm Western Power says it is investigating and could not confirm this was the cause of the blue flash.Crisis situations: For other emergency situations such as mine rescue, nuclear accidents, mountain rescue and bomb disposal.

Blue-blocking sunglasses and camera filters take the haze out of hazy scenes, because the haze is scattered blue light. They saw a bright flash 100 times brighter than the usual supernova, the brightest explosion humanity has seen. If there are large obstructions in the wall such as doors and windows, multiply the width by the height of the obstruction then subtract that from the total area you need to tile.The initial detection of the event known as AT2018cow happened in June 2018, when it was seen by a survey in Hawaii, which quickly sent out global alerts to tell other telescopes to look towards it.