NGC 6541

NGC 6541 (also known as Caldwell 78) is a globular cluster of stars in the southern constellation of Corona Australis. The globular cluster was discovered by Niccolò Cacciatore at the Palermo Astronomical Observatory, Sicily, on March 19, 1826. It was independently found by James Dunlop on July 3, 1826. The cluster has an apparent visual magnitude of 6.3 and an angular diameter of 15′. It is visible with binoculars or a small telescope.^[4]

NGC 6541
NGC 6541, imaged by the Hubble Space Telescope
Observation data (J2000 epoch)
Class	III[1]
Constellation	Corona Australis
Right ascension	18h 08m 02.36s[2]
Declination	–43° 42′ 53.6″[2]
Distance	24.8 ± 0.3 kly (7.6 ± 0.1 kpc)[3]
Apparent magnitude (V)	6.3[4]
Apparent dimensions (V)	15′[4]
Physical characteristics
Mass	5.72×105[5] M☉
Metallicity	[Fe/H] = –1.53[6] dex
Estimated age	12.93 Gyr[6]
Other designations	NGC 6541, Caldwell 78[7]
See also: Globular cluster, List of globular clusters

Located at a distance of 24.8 kly (7.6 kpc) from the Sun,^[3] it is orbiting within the central region of the Milky Way about 7.2 kly (2.2 kpc) from the Galactic Center.^[8] It is considered a metal-poor inner halo cluster, being the third most metal-poor globular cluster within 9.8 kly (3 kpc) of the center.^[8] The cluster has 5.72×10⁵ times the mass of the Sun.^[5] It is estimated to be around 12.9 billion years old,^[6] and is believed to have undergone core collapse.^[8] A total of 94 blue straggler members have been identified,^[9] as well as three W Ursae Majoris and nine SX Phoenicis variables.^[10]