Astrophoto Friday returns with a pair of photos of the galaxy known as NGC 5253.
The photo on the left was taken with Palomar's 48-inch Schmidt telescope (now known as the Samuel Oschin Telescope) the night of June 4, 1959 by Milton Humason. The right-hand picture was taken by Charles Kowal with the same telescope the night of May 16, 1972.
Notice that the photo on the right has an extra star, visible to the lower right of the brightest part of the galaxy. The photo on the right has captured an explosion known as a supernova. This particular supernova (SN 1972e) was classified as a Type Ia supernova, which is thought to occur with the explosion of a dead star known as a white dwarf.
Supernova 1972e was found as a part of an organized survey for supernovae at Palomar that photographed thirteen of them in 1972. The old technique of photographing the sky and comparing the new images with older ones taken years before has now been supplanted by surveys that scan large volumes of sky and compare the new pictures with ones taken often days earlier. The Palomar Transient Factory survey has, at last count, bagged 622 supernovae since they began scanning the skies (also with Palomar's 48-inch telescope) last year.
That's quite an improvement, wouldn't you say?