Amateur astronomer discovers faint galaxy that computers missed
Giuseppe Donatiello, an amateur astronomer, spotted a faint galaxy that a computer algorithm failed to distinguish. This discovery was later confirmed using the Hubble Space Telescope. The galaxy in question is Donatiello II. It is among the three galaxies that escaped the attention of the algorithm designed to look through astronomical data in search of galaxy candidates.
Why does this story matter?
Being a dwarf galaxy, which typically possesses low luminosity, Donatiello II is so faint that it took human intervention to uncover its existence. It is not often that computer algorithms fall short of performing their task. But once in a while, that happens, as is the case with Donatiello II. But nothing seems to escape the eye of an astronomer, does it?
Donatiello II is seen as a small, "irregularly-shaped" galaxy
In the image, Donatiello II is seen as a small, "irregularly-shaped" galaxy. It is composed of several small stars and a few slightly larger, luminescent ones, and is surrounded by a dim glow that runs along the borders of the galaxy. While the backdrop is mostly dark, a number of stars and galaxies of varying sizes can be seen.
"Even the best algorithms have their limitations"
"Even the best algorithms have their limitations when it comes to distinguishing very faint galaxies from individual stars and background noise," said ESA. "In such challenging situations, identification must be done the old-fashioned way-by a dedicated human trawling through the data themselves."
The galaxies were discovered based on the Dark Energy Survey
Alongside Donatiello II, two other galaxies identified were Donatiello III and IV. The discoveries of the galaxies were made possible from the data collected by the Dark Energy Survey (DES), a six-year-long observation spanning from 2013 to 2019. The survey was carried out using the Dark Energy Camera, mounted on the Víctor M. Blanco 4-metre Telescope at Cerro Tololo Inter-American Observatory, in Chile.
The Donatiello galaxies orbit the Sculptor Galaxy
The three Donatiello galaxies orbit the Sculptor Galaxy, also known as NGC 253, which implies that the galaxies are gravitationally bound. Using Hubble, a team of astronomers carried out an independent search of several faint galaxies, including Donatiello II, further confirming the discovery.
