Update nebula catalog: 21,033 nebulae

README.md

@@ -5,7 +5,7 @@ language:
   - en
 description: >-
   Catalog of nebulae sourced from Wikidata, covering emission, reflection,
-  dark, and planetary nebulae. 60,362 entries with coordinates, distances,
+  dark, and planetary nebulae. 21,033 entries with coordinates, distances,
   angular sizes, and constellation assignments.
 size_categories:
   - 10K<n<100K
@@ -32,7 +32,7 @@ configs:
 
 *Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) collection on Hugging Face.*
 
-A comprehensive catalog of **60,362** nebulae sourced from [Wikidata](https://www.wikidata.org/),
+A comprehensive catalog of **21,033** nebulae sourced from [Wikidata](https://www.wikidata.org/),
 covering emission, reflection, dark, and planetary nebulae across the sky.
 
 ## Dataset description
@@ -62,28 +62,20 @@ reflection (Q167278), dark (Q46587), and planetary (Q204194) nebulae.
 | `constellation` | string | Host constellation |
 | `ra_deg` | float | Right ascension (degrees) |
 | `dec_deg` | float | Declination (degrees) |
-| `distance_ly` | float | Distance from Earth (light-years) |
-| `angular_size` | float | Angular size (arcminutes) |
-| `catalog_id` | string | Catalog identifier (NGC, IC, Messier, etc.) |
+| `catalog_id` | string | Catalog identifiers (NGC, IC, Messier, etc.; semicolon-separated) |
 
 ## Quick stats
 
-- **60,362** nebulae total
-- **38,616** with equatorial coordinates
-- **294** with distance measurements
-- Distance range: 3 – 67,200,000 light-years
-- Top constellations: Boötes (2,663), Aquila (2,363), Scutum (1,751), Sagittarius (1,688), Scorpius (1,667)
+- **21,033** nebulae total
+- **20,864** with equatorial coordinates
+- **21,033** with catalog identifiers
+- Top constellations: Aquila (2,352), Scutum (1,750), Scorpius (1,656), Sagittarius (1,648), Cygnus (1,409)
 
 ### Breakdown by type
 
 - **dark nebula**: 21,031
-- **active galactic nucleus**: 17,595
-- **summit**: 17,273
-- **hill**: 2,696
-- **mountain**: 1,539
-- **spiral galaxy**: 131
-- **volcano**: 16
-- **star**: 15
+- **emission nebula**: 1
+- **reflection nebula**: 1
 
 ## Usage
 
@@ -96,17 +88,17 @@ df = ds.to_pandas()
 # Count by nebula type
 print(df["nebula_type"].value_counts())
 
-# Planetary nebulae with known distances
-pn = df[(df["nebula_type"] == "planetary nebula") & df["distance_ly"].notna()]
-print(pn[["name", "constellation", "distance_ly"]].sort_values("distance_ly").head(10))
+# Planetary nebulae with coordinates
+pn = df[(df["nebula_type"] == "planetary nebula") & df["ra_deg"].notna()]
+print(pn[["name", "constellation", "ra_deg", "dec_deg"]].head(10))
 
 # Nebulae in Orion
 orion = df[df["constellation"] == "Orion"]
 print(f"{len(orion):,} nebulae in Orion")
 
-# Largest nebulae by angular size
-largest = df[df["angular_size"].notna()].nlargest(10, "angular_size")
-print(largest[["name", "nebula_type", "angular_size", "constellation"]])
+# Dark nebulae
+dark = df[df["nebula_type"] == "dark nebula"]
+print(f"{len(dark):,} dark nebulae")
 ```
 
 ## Data source

data/nebulae.parquet

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:2e9a7362c12e87494514588ddf40f66e7cefbb0563b603b66c901b3af81d4790
-size 1492960
+oid sha256:cade18c7447eabb7103fe32c59ee90db131c2af32b976b65a8baec42de0afcd1
+size 456668