Globular cluster · Ophiuchus

M10

Also known as: NGC 6254

mag 6.615′ across

About

M10 is a globular cluster of magnitude 6.6 in Ophiuchus, about 15′ across.

M10 is in the constellation Ophiuchus.
Best evenings: around late July it is highest at about 9 pm (10 pm in summer time); a month earlier, two hours later.
Where on Earth: it is seen well, at least 10° up, from south of 76° N.

When it rises and sets tonight, how high it climbs and how much the Moon gets in the way are worked out in your browser for your place.

EyesNot visible to the naked eye.
Binoculars (10×50)A fuzzy ball, brighter towards the middle.
Telescope (6–8 inch)Resolves into a swarm of stars at medium power, with a dense core.

For a dark country sky with no Moon. From a city, faint galaxies and nebulae can disappear completely.

Designations	M10, NGC 6254
Type	Globular cluster
Magnitude	6.6The smaller the number, the brighter.
Apparent size	15′the full Moon is 31′ across
Surface brightness	≈ 21.1 mag/arcsec²Estimate from the magnitude and size, per square arcsecond.
Constellation	Ophiuchus
Right ascension (J2000)	16h 57m 09.0s
Declination (J2000)	−04° 05′ 57″