Smack dab in the center of this Hubble telescope image, between distant stars and even more distant galaxies, is the newly discovered dwarf galaxy known as Donatiello II.
Donatiello II is one of three newly discovered galaxies so difficult to detect that were not detected by an algorithm designed to search for candidate galaxies in astronomical data.
Even the best algorithms have their limitations when it comes to distinguishing very faint galaxies from individual stars and from background noise. ANDIn the most difficult cases, discoveries must be made the old-fashioned way, that is, by a human being dedicated to trawling the data, explains NASA in a statement.
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The data that allowed these discoveries were collected by the Dark Energy Survey (DES) and were processed and analyzed by the amateur astronomer Giuseppe Donatiello. Analysis of it resulted in three very faint galaxies, now named Donatiello II, III and IV respectively. All three are satellites of the well-known Sculptor galaxy (also known as NGC 253), which means that they are gravitationally bound to their much more massive companion.
This image is from a NASA/ESA Hubble Space Telescope Observing Program. Based on their own independent search, a team led by Burçin Mutlu-Pakdil used Hubble to obtain long-exposure images of several faint galaxies, including Donatiello II. With the Hubble images, they were able to confirm the association of their target galaxies with NGC 253 – thus providing both independent confirmation of Donatiello’s discovery, like this image.