About NGC 4103
NGC 4103 is a rare cluster. It sits in the constellation Cru and shines at apparent magnitude 7.4.
An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Rare cluster 34 EP
NGC 4103
RA 181.6649° · Dec -61.2501° · openngc
Score breakdown
· 5 badgesRare 50 pts → Epic
- Coming towards us +10
- Under the Southern Cross +8
- Star cluster +7
- Bright deep-sky object +6
- Open cluster +3
Total score 34
16 more points to reach Epic.
Badges
- Star cluster · +7
- Bright deep-sky object · +6
- Open cluster · +3
- Under the Southern Cross · +8
- 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 7.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Crux.
- Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
- Best time of year. It stands highest in the middle of the night around March — 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 New General Catalogue. Its NGC number comes from J. L. E. Dreyer's 1888 catalogue, itself built on decades of sky sweeps by William Herschel and his sister Caroline.
Properties
- constellation
- Cru
- dso type
- OCl
- mag
- 7.4
- name
- NGC 4103
- radial velocity kms
- -12
- size arcmin
- 7.8
Nearby objects
How to see it
Look for NGC 4103 in the constellation Cru. At apparent magnitude 7.4, it is an easy target for binoculars.
Like any astronomical target, NGC 4103 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 NGC 4103 is a rare cluster
NGC 4103 scores 34 points on Spacedle's rarity scale, which places it in the rare tier. Another 16 points would lift it into a rarer tier.
That score comes from 5 science badges — Star cluster, Bright deep-sky object, Open cluster, Under the Southern Cross 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.