σ Sgr. Magnitude 2.02, blue-white. Comfortably visible to the naked eye from a suburban sky.
Astronomers call it σ Sgr — the Bayer designation, which reads as a Greek letter ranking its brightness within its constellation. Nunki is the name people actually use.
Nunki shines at magnitude 2.02, making it comfortably visible to the naked eye from a suburban sky. Its B−V colour index of -0.22 makes it blue-white to the eye, corresponding to a surface temperature of over 10,000 K.
It sits at right ascension 18.92 hours and declination -26.3°. It lies south of the celestial equator and sits low for northern observers, better the further south you go.
SkyRef shows exactly where Nunki is from your location right now — altitude, compass direction, and rise and set times.