Astronomers see black hole raging red
The inset shows a movie of fast red flashes from V404 Cygni observed by the ULTRACAM fast imager on the William Herschel Telescope in the early morning hours of June 26, 2015. A ~6 second segment of the ULTRACAM movie is repeated continuously. The flashes are incredibly short and last less than one second, with some of them being even faster than 1/40-th of a second. The flashes are equivalent to a luminosity of about 1,000 times the Sun's power. The background image shows a region of the sky in the Cygnus constellation, with the Cygnus Loop supernova remnant on the bottom left.
A still image showing one of the frames with a red flash from the above movie. The frame is only 1/40th of a second in exposure time (Please also refer to the caption of the first figure for reference).