COSMOS / CONSTELLATIONS / SGR
Sagittarius (Archer)
The Archer. IAU abbreviation Sgr. One of the 48 classical constellations listed by Ptolemy in the Almagest in the 2nd century AD.
STAR CHART
KEY FACTS
- IAU abbreviation
- Sgr
- Latin name / genitive
- Sagittarius / Sagittarii
- Position
- Right ascension ≈ 19 h 03 m; declination −45° to −12°
- Visibility from Türkiye
- Visible in full from anywhere in Türkiye. When it crosses the meridian its centre stands about 21° above the horizon from Ankara.
- Best time to observe
- Best placed at 21:00 Türkiye time around 3 September.
- Number of stars
- 199 stars brighter than magnitude 6.5 in the catalogue; 41 brighter than 5 and 16 brighter than 4.
INTERACTIVE LAB
Where is Sagittarius tonight?
The lab opens for Ankara on today’s date. Drag the time slider through the night; the “Best night” button jumps to the date when the constellation is highest at 21:00 (around 3 September). Change the city to compare the view from elsewhere in Türkiye and around the world.
MYTH, HISTORY AND OBSERVING
A zodiac constellation drawn as a centaur drawing a bow; its bright stars form a distinctive “Teapot”. The centre of our Galaxy and its supermassive black hole, Sagittarius A*, lie in this direction. The Lagoon Nebula (M8), the Omega Nebula (M17) and the globular cluster M22 are here.
BRIGHTEST STARS
| Star | Magnitude | Distance (light-years) | Spectral type |
|---|---|---|---|
| Kaus Australis | 1.79 | 143 | B9.5III |
| Nunki | 2.05 | 228 | B2.5V |
| Ascella | 2.60 | 88 | A3IV |
| Kaus Media | 2.72 | 348 | K3III |
| Kaus Borealis | 2.82 | 78 | K1IIIb |
| Albaldah | 2.88 | 510 | F2II/III |
| Alnasl | 2.98 | 97 | K0III |
| η Sgr | 3.10 | 146 | M2III |
Magnitude: apparent brightness; the smaller the number, the brighter the star. Distances derive from parallax measurements and are uncertain for distant stars. Source: HYG v4.1 star catalogue (CC BY-SA 4.0).
SOURCES
Position, visibility and best observing time were computed approximately for this page from the catalogue stars (Ankara, 39.9° N). The 88 constellations were adopted by the IAU in 1922; their boundaries were drawn by Eugène Delporte in 1930.