Can You Spot It?

Esahubble_potw2306a_1024

esahubble_potw2306a February 6th, 2023

Credit: ESA/Hubble & NASA, B. Mutlu-PakdilAcknowledgement: G. Donatiello

Right in the middle of this image, nestled amongst a smattering of distant stars and even more distant galaxies, lies the newly discovered dwarf galaxy known as Donatiello II. If you cannot quite distinguish the clump of faint stars that is all we can see of Donatiello II in this image, then you are in good company. Donatiello II is one of three newly discovered galaxies that were so difficult to spot that they were all missed by an algorithm designed to search astronomical data for potential galaxy candidates. Even the best algorithms have their limitations when it comes to distinguishing very faint galaxies from individual stars and background noise. In these most challenging identification cases, discovery has to be done the old-fashioned way — by a dedicated human trawling through the data themselves.  The data that enabled these discoveries was collected by the Dark Energy Survey (DES), an intense observation effort that spanned six years, and was carried out using the Dark Energy Camera (DECam), which is mounted on the Víctor M. Blanco 4-metre Telescope at Cerro Tololo Inter-American Observatory, a Program of NSF’s NOIRLab. As is the case for most major telescopes that receive public funding, the DES data were made available to the public. That is when the experienced amateur astronomer Giuseppe Donatiello stepped in. He laboriously processed and analysed chunks of the DES data, and made his discovery — three very faint galaxies, now named Donatiello II, III and IV respectively. All three are satellites of the well known Sculptor galaxy (otherwise known as NGC 253), meaning that they are all bound gravitationally to their much more massive companion.  This image comes from an observing programme from the NASA/ESA Hubble Space Telescope. 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 their target galaxies’ association with NGC 253 — thereby providing both an independent confirmation of Donatiello’s discovery, and this new Picture of the Week. [Image description: A black, mostly empty field with a variety of stars and galaxies spread across it. Most are very small. A couple of galaxies and stars are larger with visible details. In the centre is a relatively small, irregularly-shaped galaxy; it is formed of many very small stars and a few slightly larger, bright stars, all surrounded by a very faint glow that marks the borders of the galaxy.] Links Hubble paper in the Astrophysical Journal Video of Can You Spot It?

Provider: Hubble Space Telescope | ESA

Image Source: https://esahubble.org/images/potw2306a/

Curator: ESA/Hubble, Baltimore, MD, United States

Image Use Policy: Creative Commons Attribution 4.0 International License

Image Details

Image Type
Observation
Object Name
NGC 253 Sculptor Dwarf Galaxy
Esahubble_potw2306a_128
 

Position Details

Position (ICRS)
RA = 0h 47m 7.2s
DEC = -23° 57’ 20.6”
Orientation
North is 63.9° CW
Field of View
3.2 x 1.6 arcminutes
Constellation
Cetus

Color Mapping

  Telescope Spectral Band Wavelength
Red Hubble (ACS) Optical (I) 814.0 nm
Green Hubble (ACS) Optical (V) 606.0 nm
Green Hubble (ACS) Optical (I) 814.0 nm
Blue Hubble (ACS) Optical (V) 606.0 nm
Spectrum_base
Red
Green
Green
Blue
Esahubble_potw2306a_1280
×
ID
potw2306a
Subject Category
Subject Name
NGC 253, Sculptor Dwarf Galaxy
Credits
ESA/Hubble & NASA, B. Mutlu-PakdilAcknowledgement: G. Donatiello
Release Date
2023-02-06T06:00:00
Lightyears
Redshift
Reference Url
https://esahubble.org/images/potw2306a/
Type
Observation
Image Quality
Distance Notes
Facility
Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope, Hubble Space Telescope
Instrument
ACS, ACS, ACS, ACS
Color Assignment
Red, Green, Green, Blue
Band
Optical, Optical, Optical, Optical
Bandpass
I, V, I, V
Central Wavelength
814, 606, 814, 606
Start Time
Integration Time
Dataset ID
None, None, None, None
Notes
Coordinate Frame
ICRS
Equinox
J2000
Reference Value
11.77997327793586, -23.955726328033226
Reference Dimension
3838.0, 1931.0
Reference Pixel
1919.0, 965.5
Scale
-1.3900179376048846e-05, 1.3900179376048846e-05
Rotation
-63.880000000000123
Coordinate System Projection:
TAN
Quality
Full
FITS Header
Notes
Creator (Curator)
ESA/Hubble
URL
https://esahubble.org
Name
Email
Telephone
Address
ESA Office, Space Telescope Science Institute, 3700 San Martin Dr
City
Baltimore
State/Province
MD
Postal Code
21218
Country
United States
Rights
Creative Commons Attribution 4.0 International License
Publisher
ESA/Hubble
Publisher ID
esahubble
Resource ID
potw2306a
Metadata Date
2023-02-02T16:23:41+01:00
Metadata Version
1.1
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Detailed color mapping information coming soon...

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There is no distance meta data in this image.

 

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