Messier 23 is an open cluster in Sagittarius, 2,330 light-years away
Messier 23 (M23, NGC 6494, MWSC 2757) is an open cluster in the constellation Sagittarius , 2,330 light-years away. It shines at magnitude 5.5 and spans 35′ of sky, about 24 light-years across. It is an easy target in binoculars, and it is highest in the evening sky in August.
Open cluster: a loose group of a few dozen to a few thousand young stars born together from one cloud of gas. They drift apart over a few hundred million years and lie in the disk of the Milky Way.
Finding Messier 23 from ξ Ser
ξ Ser
Messier 23
SAGITTARIUS
Messier 23 lies 5.9° southeast of ξ Ser , the magnitude 3.5 star. Three fingers held at arm's length cover about 5°.
Messier 23 is highest in the evening in August
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60°N
JAN at 60°N: -47° high at 9 pm FEB at 60°N: -48° high at 9 pm MAR at 60°N: -41° high at 9 pm APR at 60°N: -27° high at 9 pm MAY at 60°N: -12° high at 9 pm JUN at 60°N: 1° high at 9 pm JUL at 60°N: 9° high at 9 pm AUG at 60°N: 11° high at 9 pm SEP at 60°N: 5° high at 9 pm OCT at 60°N: -7° high at 9 pm NOV at 60°N: -21° high at 9 pm DEC at 60°N: -36° high at 9 pm 50°N
JAN at 50°N: -55° high at 9 pm FEB at 50°N: -58° high at 9 pm MAR at 50°N: -46° high at 9 pm APR at 50°N: -28° high at 9 pm MAY at 50°N: -9° high at 9 pm JUN at 50°N: 8° high at 9 pm JUL at 50°N: 18° high at 9 pm AUG at 50°N: 21° high at 9 pm SEP at 50°N: 13° high at 9 pm OCT at 50°N: -2° high at 9 pm NOV at 50°N: -21° high at 9 pm DEC at 50°N: -39° high at 9 pm 40°N
JAN at 40°N: -63° high at 9 pm FEB at 40°N: -67° high at 9 pm MAR at 40°N: -51° high at 9 pm APR at 40°N: -28° high at 9 pm MAY at 40°N: -6° high at 9 pm JUN at 40°N: 14° high at 9 pm JUL at 40°N: 28° high at 9 pm AUG at 40°N: 30° high at 9 pm SEP at 40°N: 20° high at 9 pm OCT at 40°N: 3° high at 9 pm NOV at 40°N: -20° high at 9 pm DEC at 40°N: -42° high at 9 pm 30°N
JAN at 30°N: -69° high at 9 pm FEB at 30°N: -75° high at 9 pm MAR at 30°N: -54° high at 9 pm APR at 30°N: -27° high at 9 pm MAY at 30°N: -2° high at 9 pm JUN at 30°N: 21° high at 9 pm JUL at 30°N: 37° high at 9 pm AUG at 30°N: 40° high at 9 pm SEP at 30°N: 28° high at 9 pm OCT at 30°N: 7° high at 9 pm NOV at 30°N: -18° high at 9 pm DEC at 30°N: -43° high at 9 pm 20°N
JAN at 20°N: -71° high at 9 pm FEB at 20°N: -80° high at 9 pm MAR at 20°N: -54° high at 9 pm APR at 20°N: -25° high at 9 pm MAY at 20°N: 1° high at 9 pm JUN at 20°N: 27° high at 9 pm JUL at 20°N: 46° high at 9 pm AUG at 20°N: 50° high at 9 pm SEP at 20°N: 35° high at 9 pm OCT at 20°N: 12° high at 9 pm NOV at 20°N: -15° high at 9 pm DEC at 20°N: -43° high at 9 pm 10°N
JAN at 10°N: -69° high at 9 pm FEB at 10°N: -76° high at 9 pm MAR at 10°N: -52° high at 9 pm APR at 10°N: -23° high at 9 pm MAY at 10°N: 5° high at 9 pm JUN at 10°N: 32° high at 9 pm JUL at 10°N: 54° high at 9 pm AUG at 10°N: 60° high at 9 pm SEP at 10°N: 41° high at 9 pm OCT at 10°N: 16° high at 9 pm NOV at 10°N: -13° high at 9 pm DEC at 10°N: -40° high at 9 pm 0°
JAN at 0°: -63° high at 9 pm FEB at 0°: -68° high at 9 pm MAR at 0°: -48° high at 9 pm APR at 0°: -20° high at 9 pm MAY at 0°: 8° high at 9 pm JUN at 0°: 37° high at 9 pm JUL at 0°: 62° high at 9 pm AUG at 0°: 69° high at 9 pm SEP at 0°: 47° high at 9 pm OCT at 0°: 19° high at 9 pm NOV at 0°: -9° high at 9 pm DEC at 0°: -37° high at 9 pm 10°S
JAN at 10°S: -55° high at 9 pm FEB at 10°S: -59° high at 9 pm MAR at 10°S: -42° high at 9 pm APR at 10°S: -16° high at 9 pm MAY at 10°S: 11° high at 9 pm JUN at 10°S: 40° high at 9 pm JUL at 10°S: 68° high at 9 pm AUG at 10°S: 77° high at 9 pm SEP at 10°S: 51° high at 9 pm OCT at 10°S: 23° high at 9 pm NOV at 10°S: -6° high at 9 pm DEC at 10°S: -32° high at 9 pm 20°S
JAN at 20°S: -46° high at 9 pm FEB at 20°S: -50° high at 9 pm MAR at 20°S: -36° high at 9 pm APR at 20°S: -12° high at 9 pm MAY at 20°S: 14° high at 9 pm JUN at 20°S: 42° high at 9 pm JUL at 20°S: 70° high at 9 pm AUG at 20°S: 81° high at 9 pm SEP at 20°S: 53° high at 9 pm OCT at 20°S: 25° high at 9 pm NOV at 20°S: -2° high at 9 pm DEC at 20°S: -27° high at 9 pm 30°S
JAN at 30°S: -37° high at 9 pm FEB at 30°S: -40° high at 9 pm MAR at 30°S: -29° high at 9 pm APR at 30°S: -8° high at 9 pm MAY at 30°S: 17° high at 9 pm JUN at 30°S: 43° high at 9 pm JUL at 30°S: 68° high at 9 pm AUG at 30°S: 76° high at 9 pm SEP at 30°S: 52° high at 9 pm OCT at 30°S: 27° high at 9 pm NOV at 30°S: 1° high at 9 pm DEC at 30°S: -21° high at 9 pm 40°S
JAN at 40°S: -28° high at 9 pm FEB at 40°S: -30° high at 9 pm MAR at 40°S: -21° high at 9 pm APR at 40°S: -3° high at 9 pm MAY at 40°S: 18° high at 9 pm JUN at 40°S: 42° high at 9 pm JUL at 40°S: 62° high at 9 pm AUG at 40°S: 68° high at 9 pm SEP at 40°S: 50° high at 9 pm OCT at 40°S: 28° high at 9 pm NOV at 40°S: 5° high at 9 pm DEC at 40°S: -15° high at 9 pm
below horizon
low
20-40°
40-60°
overhead-ish
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole southern hemisphere and north to about 71°N, and never sets south of 71°S.
Messier 23 is 2,330 light-years away
The light seen from Messier 23 tonight left it about 2,330 years ago. It ranks 14 of 109 by distance among the 110 Messier objects. Distance source: Gaia DR3, Hunt and Reffert 2023.
Objects within 6° of Messier 23
NGC 6445 Box Nebula, planetary nebula, 2.1° NGC 6440, globular cluster, 2.4° M21, open cluster, 3.9° M20 Trifid Nebula, nebula w/cluster, 4.2° NGC 6568, open cluster, 4.5° M24 Small Sagittarius Star Cloud, cloud, 4.7° NGC 6583, open cluster, 5.4° M8 Lagoon Nebula, nebula w/cluster, 5.6°
Messier 23 catalog data
Field Value
Designations M23, NGC 6494, MWSC 2757 Type open cluster Constellation Sagittarius Right ascension (J2000) 17h 57.1m Declination (J2000) -18° 59′ Magnitude 5.5 Apparent size 35′ True size 24 light-years Distance 2,330 light-years (Gaia DR3, Hunt and Reffert 2023) Best month August Best with Binoculars Messier marathon order 95
