About IC 166
IC 166 is an uncommon cluster. It sits in the constellation Cas and shines at apparent magnitude 11.7.
An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Uncommon cluster 24 EP
IC 166
RA 28.0993° · Dec 61.8526° · openngc
Score breakdown
· 4 badgesUncommon 34 pts → Rare
- Coming towards us +10
- Star cluster +7
- Never sets (northern circumpolar) +4
- Open cluster +3
Total score 24
10 more points to reach Rare.
Badges
- Star cluster · +7
- Open cluster · +3
- Never sets (northern circumpolar) · +4
- Coming towards us · +10
Trivia
What it actually is
- What it actually is. An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Sense of scale
- Sense of scale. Gravity is not strong enough to hold it. Within a few hundred million years these siblings will be scattered right around the galaxy.
Find it in the sky
- How to spot it. At magnitude 11.7 you'll want a small backyard telescope, over in Cassiopeia.
- Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
- Best time of year. It stands highest in the middle of the night around October — that's when to go looking.
Its true colour
- Its true colour. Open clusters look blue-white because they are young — their hottest, bluest stars have not had time to die yet.
How we came to know it
- The Index Catalogue. The IC was the 1895 and 1908 supplement to the NGC — the first catalogue in history to be filled largely with objects found on photographic plates rather than by eye.
Properties
- constellation
- Cas
- dso type
- OCl
- mag
- 11.7
- name
- IC 166
- radial velocity kms
- -40
- size arcmin
- 7.5
How to see it
Look for IC 166 in the constellation Cas. At apparent magnitude 11.7, a small backyard telescope will bring it into view.
Like any astronomical target, IC 166 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.
Why IC 166 is an uncommon cluster
IC 166 scores 24 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 10 points would lift it into a rarer tier.
That score comes from 4 science badges — Star cluster, Open cluster, Never sets (northern circumpolar) and Coming towards us — 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.