NGC 3918
E498147
NGC 3918 is a bright planetary nebula in the southern sky, often called the "Blue Planetary" due to its vivid blue appearance.
All labels observed (1)
| Label | Occurrences |
|---|---|
| NGC 3918 canonical | 3 |
How this entity was disambiguated
This entity first appeared as the object of triple T4943595 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: NGC 3918 Context triple: [Centaurus constellation region, contains, NGC 3918]
-
A.
NGC 4609
NGC 4609 is an open star cluster located in the southern constellation Centaurus, notable for its relatively young stellar population.
-
B.
NGC 3372
NGC 3372 is a massive, bright star-forming nebula in the Carina constellation, famous for housing the unstable supergiant star Eta Carinae and extensive regions of ionized gas and dust.
-
C.
NGC 598
NGC 598 is the Triangulum Galaxy, a nearby spiral galaxy in the Local Group and one of the closest large galaxies to the Milky Way.
-
D.
NGC 2976
NGC 2976 is a nearby dwarf spiral galaxy in the constellation Ursa Major and a member of the M81 Group of galaxies.
-
E.
NGC 3766
NGC 3766 is a young open star cluster notable for its rich population of hot, massive stars and unusual variable stars, located in the southern sky.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: NGC 3918 Target entity description: NGC 3918 is a bright planetary nebula in the southern sky, often called the "Blue Planetary" due to its vivid blue appearance.
-
A.
NGC 4609
NGC 4609 is an open star cluster located in the southern constellation Centaurus, notable for its relatively young stellar population.
-
B.
NGC 3372
NGC 3372 is a massive, bright star-forming nebula in the Carina constellation, famous for housing the unstable supergiant star Eta Carinae and extensive regions of ionized gas and dust.
-
C.
NGC 598
NGC 598 is the Triangulum Galaxy, a nearby spiral galaxy in the Local Group and one of the closest large galaxies to the Milky Way.
-
D.
NGC 2976
NGC 2976 is a nearby dwarf spiral galaxy in the constellation Ursa Major and a member of the M81 Group of galaxies.
-
E.
NGC 3766
NGC 3766 is a young open star cluster notable for its rich population of hot, massive stars and unusual variable stars, located in the southern sky.
- F. None of above. chosen
Statements (43)
| Predicate | Object |
|---|---|
| instanceOf | planetary nebula ⓘ |
| angularSize | approximately 20 arcseconds ⓘ |
| apparentMagnitudeV | 8.5 ⓘ |
| belongsToGalaxy | Milky Way ⓘ |
| bestSeenWith | small to medium amateur telescopes ⓘ |
| carriesCaldwellNumber | C90 ⓘ |
| catalog |
Caldwell catalogue
ⓘ
New General Catalogue ⓘ |
| catalogNumber | NGC 3918 ⓘ |
| centralStar | hot white dwarf ⓘ |
| color | blue ⓘ |
| declination | −57° 11′ ⓘ |
| discoveredBy | John Herschel ⓘ |
| discoveryYear | 1834 ⓘ |
| distanceFromEarth |
approximately 1.5 kiloparsecs
ⓘ
approximately 4900 light-years ⓘ |
| dominantIon | doubly ionized oxygen (O III) ⓘ |
| ejectionOrigin | outer layers of a dying star ⓘ |
| excitationClass | high-excitation planetary nebula ⓘ |
| galacticLatitude | +11.7 degrees (approximate) ⓘ |
| galacticLongitude | 294.6 degrees (approximate) ⓘ |
| hasAlternativeName |
Blue Planetary
ⓘ
Caldwell 90 ⓘ The Blue Planetary ⓘ
linked to:
Blue Planetary
|
| hasEmission | ionized gas ⓘ |
| hasStructure |
bright inner shell
ⓘ
fainter outer halo ⓘ |
| hemisphere | southern sky ⓘ |
| isTargetFor |
amateur astronomers
ⓘ
planetary nebula evolution studies ⓘ |
| locatedInConstellation | Centaurus ⓘ |
| morphologicalType | elliptical planetary nebula ⓘ |
| notableFor | vivid blue appearance ⓘ |
| observationalClass | bright planetary nebula ⓘ |
| observedIn |
infrared wavelengths
ⓘ
optical wavelengths ⓘ radio wavelengths ⓘ |
| phaseOfStellarEvolution | late stage of low- to intermediate-mass star ⓘ |
| rightAscension | 11h 50m ⓘ |
| skyRegion | near the Crux–Centaurus area ⓘ |
| spectralFeatures | strong [O III] emission lines ⓘ |
| surfaceBrightness | high ⓘ |
| visibilitySeason | autumn and winter in Southern Hemisphere ⓘ |
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: NGC 3918 Description of subject: NGC 3918 is a bright planetary nebula in the southern sky, often called the "Blue Planetary" due to its vivid blue appearance.
Referenced by (3)
Full triples — surface form annotated when it differs from this entity's canonical label.