V1500 Cygni or Nova Cygni 1975 was a bright nova occurring in 1975 in the constellation Cygnus. It had the second highest intrinsic brightness of any nova of the 20th century, exceeded only by CP Puppis in 1942.
Nova Cygni 1975 (center), photographed at 07:00 UT August 30, 1975. Also shown are 59 Cygni (magnitude 4.8), 60 Cygni (magnitude 5.4) and 63 Cygni (magnitude 4.5)
A nova is a transient astronomical event that causes the sudden appearance of a bright, apparently "new" star that slowly fades over weeks or months. All observed novae involve white dwarfs in close binary systems, but causes of the dramatic appearance of a nova vary, depending on the circumstances of the two progenitor stars. The main sub-classes of novae are classical novae, recurrent novae (RNe), and dwarf novae. They are all considered to be cataclysmic variable stars.
Artist's conception of a white dwarf, right, accreting hydrogen from the Roche lobe of its larger companion star
Nova Eridani 2009 (apparent magnitude ~8.4)
GK Persei: Nova of 1901
Nova in Andromeda Galaxy