Stephan's Quintet - Hubble Space Telescope (Rudy Pohl)

Stephan's Quintet - Hubble Space Telescope

Stephan's Quintet is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. The group, visible in the constellation Pegasus, was discovered by Édouard Stephan in 1877 at the Marseille Observatory. The group is the most studied of all the compact galaxy groups. (Wikipedia)

Note 1:

If you are wondering where the five galaxies area and can only count four, the structure in the upper right-hand position which looks like a smiling face is actually composed of two galaxies interacting together - NGC 7318A and NGC 7318B.

Note 2:

Redshift - Stephan's Quintet => Hickson Quartet

NGC 7320, the blue-ish spiral galaxy in the lower left has a redshift of only 790 km/s, while the other four galaxies exhibit a much larger redshift of approx. 6600 km/s. Since galactic redshift is proportional to the distance from Earth, NGC 7320 is actually not part of this grouping but only appears that way. It is located in front of the other four by about 39 million light years from Earth versus the 210-340 million light years of the other four. This has caused some astronomers to call the other four the "Hickson Quartet" rather than Stephan's Quintet.

Data acquisition: Hubble Legacy Archive, NASA

Data processing: Rudy Pohl

Image: RGB colour

Processing software: Fits Liberator, Photoshop CS5

Original
B
C
Final
D

Please note: The following tables are updated every 24 hours.

Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

Status	Basic failed
Started	...
Astrometry.net job	3121995
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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