Open star cluster M25
Open star cluster M25 is in the constellation Sagittarius (Sgr).
Equatorial coordinates (epoch J2000):
Ra 18h 31.6m, Dec -19° 15'
Visual magnitude: 4,9m - this object can be seen with the naked eye on a black sky, in the absence of illumination from street lighting.
Distance to the star clusters M25 to the Sun is 2020 light years
Angular size: 30'
External dimensions the star clusters M25 are about 17 light years.
Number of stars: 220
Age of the object M25 is 100x106 years
Discoverer: Jean-Philippe Loys de Chéseaux, 1745 year.
The designation M25 in other catalogs: IC 4725
Optimum magnification for a telescope with observations of M25, depending on the aperture of the telescope (D), is about 10x-30x. 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 M25 is July.
For observers in the northern latitudes:
The nights in July are still quite light, so it makes sense to try to observe M25 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.
or tell your friends: