NGC 2261
E546408
NGC 2261, also known as Hubble's Variable Nebula, is a small, fan-shaped reflection nebula in the constellation Monoceros whose appearance changes over time due to variations in its illuminating star.
All labels observed (1)
| Label | Occurrences |
|---|---|
| NGC 2261 canonical | 4 |
How this entity was disambiguated
This entity first appeared as the object of triple T5775486 — 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 2261 Context triple: [Monoceros, contains, NGC 2261]
-
A.
NGC 2362
NGC 2362 is a young, bright open star cluster dominated by the massive star Tau Canis Majoris, located in the constellation Canis Major.
-
B.
NGC 2264
NGC 2264 is a prominent star-forming region in the constellation Monoceros that includes the Cone Nebula and the Christmas Tree Cluster.
-
C.
NGC 6925
NGC 6925 is a barred spiral galaxy located in the constellation Microscopium.
-
D.
NGC 6809
NGC 6809 is a bright, relatively nearby globular star cluster in the constellation Sagittarius, notable for its loose structure and rich population of ancient stars.
-
E.
NGC 2071
NGC 2071 is a reflection nebula and active star-forming region located in the constellation Orion, associated with the larger Orion B molecular cloud.
- 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 2261 Target entity description: NGC 2261, also known as Hubble's Variable Nebula, is a small, fan-shaped reflection nebula in the constellation Monoceros whose appearance changes over time due to variations in its illuminating star.
-
A.
NGC 2362
NGC 2362 is a young, bright open star cluster dominated by the massive star Tau Canis Majoris, located in the constellation Canis Major.
-
B.
NGC 2264
NGC 2264 is a prominent star-forming region in the constellation Monoceros that includes the Cone Nebula and the Christmas Tree Cluster.
-
C.
NGC 6925
NGC 6925 is a barred spiral galaxy located in the constellation Microscopium.
-
D.
NGC 6809
NGC 6809 is a bright, relatively nearby globular star cluster in the constellation Sagittarius, notable for its loose structure and rich population of ancient stars.
-
E.
NGC 2071
NGC 2071 is a reflection nebula and active star-forming region located in the constellation Orion, associated with the larger Orion B molecular cloud.
- F. None of above. chosen
Statements (46)
| Predicate | Object |
|---|---|
| instanceOf |
reflection nebula
ⓘ
variable nebula ⓘ |
| alsoKnownAs |
Hubble's Variable Nebula
ⓘ
linked to:
Hubble’s Variable Nebula
Hubbles Variable Nebula ⓘ
linked to:
Hubble’s Variable Nebula
|
| angularSize | 2.0 × 1.0 arcminutes ⓘ |
| apparentMagnitudeV | 9.0 ⓘ |
| associatedStar | R Monocerotis ⓘ |
| associatedWith |
young stellar object R Monocerotis
ⓘ
linked to:
Herbig Ae/Be stars
|
| belongsTo | Milky Way ⓘ |
| bestSeenIn |
medium telescopes
ⓘ
small telescopes ⓘ |
| catalogCode | NGC 2261 ⓘ |
| catalogIn | NGC ⓘ |
| declination | +08° 44′ 10″ ⓘ |
| discoveredBy | William Herschel ⓘ |
| discoveryDate | 1783 ⓘ |
| discoveryInstrument | reflecting telescope ⓘ |
| distanceFromEarth |
2500 light-years
ⓘ
770 parsecs ⓘ |
| equatorialCoordinateSystem | J2000 ⓘ |
| galacticLatitude | -2.3° ⓘ |
| galacticLongitude | 203.1° ⓘ |
| hasColor | bluish ⓘ |
| hasVariableAppearance | true ⓘ |
| hemisphereVisibility | Northern Hemisphere ⓘ |
| illuminatedBy | R Monocerotis ⓘ |
| illuminationMechanism | starlight scattered by dust ⓘ |
| locatedIn | Orion Arm ⓘ |
| locatedInConstellation | Monoceros ⓘ |
| namedAfter | Edwin Hubble ⓘ |
| near | R Monocerotis ⓘ |
| nebulaType | reflection nebula ⓘ |
| notableFor |
being one of the first nebulae studied for structural variability
ⓘ
rapid changes in appearance over timescales of weeks to months ⓘ |
| objectType | NGC object ⓘ |
| observedBy | Edwin Hubble ⓘ |
| observedIn |
infrared
ⓘ
visible light ⓘ |
| partOf | New General Catalogue ⓘ |
| regionType | star-forming region ⓘ |
| rightAscension | 06h 39m 10s ⓘ |
| shape | fan-shaped ⓘ |
| variabilityCause |
changes in illumination from R Monocerotis
ⓘ
variable obscuration by dust near the illuminating star ⓘ |
| variationTimescale | weeks to months ⓘ |
| visibleInSeason | winter ⓘ |
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 2261 Description of subject: NGC 2261, also known as Hubble's Variable Nebula, is a small, fan-shaped reflection nebula in the constellation Monoceros whose appearance changes over time due to variations in its illuminating star.
Referenced by (4)
Full triples — surface form annotated when it differs from this entity's canonical label.