M22 (George Simon)

Celestial hemisphere: Southern · Constellation: Sagittarius (Sgr) · Contains: M 22 · NGC 6656

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M22

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M22

Because, at first glance, most globular clusters appear almost identical to every other globular cluster that one has ever observed, globs tend to be underappreciated and less frequently imaged by astrophotographers. However, more careful consideration reveals that most globs can, in fact be distinguished from each other. Such is certainly the case for M22, the Sagittarius Cluster. To begin with, because it lies between us and a portion of the Milky Way's central galactic bulge, it is not set against the sparse star field that typically surrounds most other globular clusters. Instead, it is set against a dense and colorful star field. Next, it is considerably less spherical than the "average" glob; it is, in fact, elliptical, with its major axis running from the upper left to the lower right in my image. M22 is also distinguished by the fact that it is one of only four Milky Way globs known to contain a planetary nebula. It has also been found to contain two stellar-mass black holes. The discovery of these black holes has led astronomers to conclude that stellar-mass black holes are not ejected as efficiently from globs as previously thought. As a result, M22 is conjectured to contain anywhere from 5 to 100 such black holes lurking within its 70-light-year diameter. Finally, Hubble has revealed the presence of 6 planet-sized objects within M22, not gravitationally bound to any particular star. These might be rogue planets and/or brown dwarfs. An appreciation of all these distinguishing characteristics certainly leads to the conclusion that, first appearances notwithstanding, the Sagittarius Cluster is not just another big ball of stars!

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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 success
Started	...
Astrometry.net job	4830634
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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