UGC 1840

UGC 1840 known as Arp 145, are a pair of interacting galaxies located 250 million light-years away from the Solar System in the Andromeda constellation. Made up of two galaxies, UGC 1840 NED01 (PGC 9060) and UGC 1840 NED02 (PGC 9062), the two galaxies had recently collided with each other in which the elliptical galaxy has penetrated through the spiral galaxy's nucleus leaving a hole in its middle, thus forming a ring galaxy. With a diameter of 1.3 arc minutes, close to 100,000 thousand light-years, they are roughly the same size as the Milky Way.

Both galaxies are included in Atlas of Peculiar Galaxies which was created by Halton Arp. They fall under the category of objects that have emanating material and both classified as galaxies that have ring systems.