Donatiello I

Donatiello I is named after its discoverer, Italian amateur astronomer and astrophotographer Giuseppe Donatiello, and is abbreviated to "Do I". The galaxy's nickname, "Mirach's Goblin", is a reference to the nearby dwarf lenticular galaxy NGC 404, with which it may be physically associated. NGC 404 is nicknamed "Mirach's Ghost" due to its proximity to the second magnitude star Mirach. == Characteristics ==

Donatiello I is a dwarf spheroidal galaxy at an estimated distance from Earth between 2.5 and 3.5 megaparsecs, or 8.1 and 11.4 million light-years, Its luminosity is around 200,000 times greater than that of the Sun, with an absolute magnitude of around −8.3 and a surface brightness of 26 magnitudes per negative square arcsecond. Its effective radius is roughly estimated to be 400 parsecs, while its ellipticity is around 0.7. Donatiello I is one of the most isolated dwarf spheroidals known, and is a possible satellite galaxy of its nearest neighbor, NGC 404, Donatiello I could have either been involved in, or affected by, a possible merger between NGC 404 and an irregular dwarf galaxy around 900 million years ago. Like similar dwarf spheroidal galaxies orbiting the Milky Way Galaxy and Andromeda Galaxy, Donatiello I is populated with metal-poor red dwarfs, with no active star formation occurring. == Observation ==

Donatiello I lies in the constellation Andromeda, at a right ascension of and declination of , in the J2000 epoch. In the galactic coordinate system, it is located at a longitude of 127.65° and a latitude of −28.08°. Amateur astronomer and astrophotographer Giuseppe Donatiello first sighted the galaxy in 2016 while surveying an archived 6000-second exposure of an area around the Andromeda Galaxy taken on 5–7 November 2010 and 5 October 2013 in the Pollino National Park, with a custom-built 12.7 centimetre telescope. Donatiello intended to capture stellar streams and dwarf galaxies around Andromeda that had been reported at the time. The discovery was corroborated using images from the Sloan Digital Sky Survey's ninth data release, which showed a faint object in the same area, to make further observations of the galaxy with the Roque de los Muchachos Observatory's Galileo National Telescope and Gran Telescopio Canarias in La Palma, Spain, on 27 November 2016. with a preprint released on arXiv in October. along with Donatiello I's size and mass. == See also ==