Caldwell 20
E491337
Caldwell 20 is a large, bright emission nebula in the constellation Cygnus, notable for its distinctive shape resembling the outline of the North American continent.
All labels observed (1)
| Label | Occurrences |
|---|---|
| Caldwell 20 canonical | 1 |
How this entity was disambiguated
This entity first appeared as the object of triple T5060528 — 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: Caldwell 20 Context triple: [North America Nebula, alsoKnownAs, Caldwell 20]
-
A.
Caldwell 74
Caldwell 74 is a bright, well-known planetary nebula in the constellation Vela, popularly called the Southern Ring Nebula.
-
B.
Caldwell
Caldwell is a surname of Scottish and English origin borne by numerous notable individuals across politics, sports, academia, and the arts.
-
C.
Caldwell
Caldwell is a city in southwestern Idaho known as part of the Boise metropolitan area and for its agricultural roots and growing wine industry.
-
D.
Barnard
Barnard is a surname and given name of English and French origin, borne by various notable individuals and institutions.
-
E.
Sandage
Sandage is a surname most notably associated with Allan R. Sandage, a prominent American astronomer known for his work on the expansion rate and age of the universe.
- 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: Caldwell 20 Target entity description: Caldwell 20 is a large, bright emission nebula in the constellation Cygnus, notable for its distinctive shape resembling the outline of the North American continent.
-
A.
Caldwell 74
Caldwell 74 is a bright, well-known planetary nebula in the constellation Vela, popularly called the Southern Ring Nebula.
-
B.
Caldwell
Caldwell is a surname of Scottish and English origin borne by numerous notable individuals across politics, sports, academia, and the arts.
-
C.
Caldwell
Caldwell is a city in southwestern Idaho known as part of the Boise metropolitan area and for its agricultural roots and growing wine industry.
-
D.
Barnard
Barnard is a surname and given name of English and French origin, borne by various notable individuals and institutions.
-
E.
Sandage
Sandage is a surname most notably associated with Allan R. Sandage, a prominent American astronomer known for his work on the expansion rate and age of the universe.
- F. None of above. chosen
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
H II region
ⓘ
deep-sky object ⓘ emission nebula ⓘ |
| alsoKnownAs | North America Nebula NERFINISHED ⓘ |
| angularSize | about 120 arcminutes ⓘ |
| apparentMagnitude | 4.0 ⓘ |
| associatedWithStar | Deneb NERFINISHED ⓘ |
| bestSeenFromHemisphere | Northern Hemisphere NERFINISHED ⓘ |
| bestViewingSeason | summer ⓘ |
| catalogCode | C20 ⓘ |
| catalogNumber | NGC 7000 NERFINISHED ⓘ |
| contains |
interstellar dust
ⓘ
interstellar gas ⓘ star-forming regions ⓘ |
| containsRegion |
Central America region
NERFINISHED
ⓘ
East Coast region NERFINISHED ⓘ Gulf of Mexico region NERFINISHED ⓘ Mexico region ⓘ |
| declination | +44° 20′ ⓘ |
| discoveredBy | William Herschel NERFINISHED ⓘ |
| discoveryYear | 1786 ⓘ |
| distanceFromEarth |
about 2600 light-years
ⓘ
about 800 parsecs ⓘ |
| dominantColor | red ⓘ |
| dominantEmissionLine | H-alpha ⓘ |
| excitedBy | nearby hot young stars ⓘ |
| galacticLatitude | about +2.0 degrees ⓘ |
| galacticLongitude | about 85.5 degrees ⓘ |
| hasDistinctiveShape | resembles outline of North American continent ⓘ |
| includedIn | New General Catalogue NERFINISHED ⓘ |
| ionizingSource | Deneb NERFINISHED ⓘ |
| locatedIn | Cygnus Arm of the Milky Way NERFINISHED ⓘ |
| locatedInConstellation | Cygnus NERFINISHED ⓘ |
| nearbyObjectOnSky | Pelican Nebula NERFINISHED ⓘ |
| observedInWavelength |
hydrogen-alpha
ⓘ
visible light ⓘ |
| observingRequirement | dark skies for best visibility ⓘ |
| partOf | Milky Way NERFINISHED ⓘ |
| partOfCatalog | Caldwell catalogue NERFINISHED ⓘ |
| rightAscension | 20h 58m ⓘ |
| separatedFromNearbyObjectBy | dark dust lane ⓘ |
| skyLocation | near star Deneb in Cygnus ⓘ |
| typeOfNebula | diffuse nebula ⓘ |
| visibleToNakedEye | as faint glow under dark skies ⓘ |
| visibleWith |
small telescope
ⓘ
wide-field binoculars ⓘ |
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: Caldwell 20 Description of subject: Caldwell 20 is a large, bright emission nebula in the constellation Cygnus, notable for its distinctive shape resembling the outline of the North American continent.
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.