47 Tucanae

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Observation data (J2000 epoch)
47 Tucanae
47 Tucanae- Image mosaic by E. Kopan (IPAC). (Field size 19.2´ × 23.3´.)
Class	III
Constellation	Tucana
Right ascension	00^h 24^m 05.67^s^[1]
Declination	-72° 04′ 52.6″^[1]
Distance	13.4 ± ? kly^{[citation needed]} (4.1 ± ? kpc)
Apparent magnitude (V)	+4.91^[1]
Apparent dimensions (V)	30′.9
Physical characteristics
Mass	kg (? M)
Radius	60 ± ? ly^[2]
V_HB	14.2
Estimated age	~ 10 Billion Years
Notable features	2nd brightest globular cluster after Omega Centauri
Other designations	NGC 104, GCl 1^[1]
See also: Globular cluster, List of globular clusters
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47 Tucanae (NGC 104) or just 47 Tuc is a globular cluster located in the constellation Tucana. It is about 13,400 light years away from Earth, and 120 light years across. It can be seen with the naked eye, and it is bright enough to earn a Flamsteed designation with a visual magnitude of 4.0. It is one of only a small number of features in the southern sky with such a designation.

47 Tucanae was discovered by Nicolas Louis de Lacaille in 1751, its southern location having hidden it from European observers until then. The cluster appears roughly the size of the full moon in the sky under ideal conditions.

It is the second brightest globular cluster in the sky (after Omega Centauri), and is noted for having a very bright and dense core. It has 22 known millisecond pulsars, and at least 21 blue stragglers near the core.^[3]

47 Tucanae is included in Sir Patrick Moore's Caldwell catalogue as C106.

NGC 104 competes with NGC 5139 for the title: Most splendid Globular Cluster in the sky. NGC 104 has two features in it's favour. It's rounder and has a more compact core. However due to location more observers go for NGC 5139.