RA 272.7945° · Dec -17.3835° · star
9 more points to reach Rare.
HD 166391 is an uncommon star. It lies about 2,470.9 light-years from Earth, sits in the constellation Sgr, shines at apparent magnitude 8.61 and has spectral type A0/A1.
Its spectrum reads A0/A1 — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
Look for HD 166391 in the constellation Sgr. At apparent magnitude 8.61, it is an easy target for binoculars.
Like any astronomical target, HD 166391 is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.
HD 166391 scores 25 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 9 points would lift it into a rarer tier.
That score comes from 5 science badges — Star, Distant (over 1,000 light-years), Toward the galactic centre, On the zodiac and White A-type star — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.