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... М21 < М22 > М23 ...

Globular star cluster M22

Globular star cluster M22 or Sagittarius star cluster is in the constellation Sagittarius (Sgr).

M22

Equatorial coordinates (epoch J2000):
Ra 18h36.4m, Dec -23° 54'

Visual magnitude: 6,5m
Distance from the star clusters M22 to the Sun is 10440 light years
Angular size: 33'
Class: VII
External dimensions the star clusters M22 are about 100 light years.
Estimated weight the star clusters: 500x103 suns

Discoverer: Johann Abraham Ihle, 1665 year.

The designation M22 in other catalogs: NGC 6656

M22 in the middle latitudes is located quite low above the horizon, so observation is difficult due to atmospheric distortions.
In the northern latitudes is not visible.Optimum magnification for a telescope with observations of M22, depending on the aperture of the telescope (D), is about D/3-0.6D. Higher magnifications of course add details, but lead to a strong drop in the brightness of the image, making it difficult to observe.
The best month for observing M22 is July.
For observers in the northern latitudes:The nights in July are still quite light, so it makes sense to try to observe M22 also in August.
The first half of August is also not very dark, in addition the object will be at midnight not at its highest point,which provides the least exposure and atmospheric distortion. But, the difference is not so noticeable.And already in the second half of August the night sky becomes quite dark for observations (although in September it will more darker).The farther south the place of your observation is located, the earlier the sky will darken - both in time on the clock and on the calendar.


Nikolay Kurdyapin, astro-map.com  
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