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... М3 < М4 > М5 ...

Globular star cluster M4

Globular star cluster M4 is in the constellation Scorpius (Sco).

M4

Equatorial coordinates (epoch J2000):
Ra 16h23.6m, Dec -26° 32'

Visual magnitude: 5,6m - this object can be seen with the naked eye on a black sky, in the absence of illumination from street lighting.
Distance from the star clusters M4 to the Sun is 5640 light years
Angular size: 35'
Class: IX
External dimensions the star clusters M4 are about 57 light years.
Estimated weight the star clusters: 100x103 suns

Discoverer: Jean-Philippe Loys de Chéseaux, 1746 year.

The designation M4 in other catalogs: NGC 6121

M4 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 M4, depending on the aperture of the telescope (D), is about D/4-D/3. 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 M4 is June.
For observers in the northern and middle latitudes:The nights in June are very light, so try to observe M4 also in May and in July.
Of course, these months are also not very dark, in addition the object is at midnight not at its highest point, whichprovides the least exposure and atmospheric distortion, but the sense is still there.The farther south the location of your observatory is located, the darker the sky will be


Nikolay Kurdyapin, astro-map.com  
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