juliensimon/cosmicflows-galaxy-distances

---
license: cc-by-4.0
pretty_name: "Cosmicflows-4 Galaxy Distances"
language:
- en
description: "The Cosmicflows-4 catalog of galaxy distances: 55,877 distance measurements from 8 methods (Tully-Fisher, SNe Ia, fundamental plane, TRGB, Cepheids, masers, SNe II, SBF). Sourced via VizieR CDS Strasbourg."
task_categories:
- tabular-classification
tags:
- space
- galaxies
- distances
- cosmology
- astronomy
- open-data
- tabular-data
size_categories:
- 10K<n<100K
configs:
- config_name: default
data_files:
- split: train
path: data/cosmicflows_galaxy_distances.parquet
default: true
---

# Cosmicflows-4 Galaxy Distances

*Part of the [Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743) collection on Hugging Face.*

The Cosmicflows-4 (CF4) catalog is the most comprehensive compilation of galaxy distances
ever assembled. Published by Tully et al. (2023), it contains **55,877** distance
measurements derived from eight independent methods, enabling studies of the cosmic
distance ladder, large-scale structure, and peculiar velocities of galaxies.

## Dataset description

Galaxy distances are fundamental to cosmology. Unlike redshifts, which mix Hubble flow
with peculiar velocities, direct distance measurements let us map the true 3D distribution
of matter. CF4 consolidates distances from Type Ia supernovae, the Tully-Fisher relation,
the fundamental plane, tip of the red giant branch (TRGB), Cepheid period-luminosity,
surface brightness fluctuations (SBF), Type II supernovae, and maser observations.

Each entry includes the PGC galaxy identifier, coordinates (equatorial, galactic,
supergalactic), CMB-frame velocity, a best-estimate distance modulus, and individual
distance moduli from each method where available.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `pgc` | int | PGC galaxy number |
| `pgc_primary` | int | Primary PGC number (for grouped galaxies) |
| `morphological_type` | float | Morphological type code (de Vaucouleurs T) |
| `velocity_cmb` | float | Velocity in CMB frame (km/s) |
| `distance_modulus` | float | Best-estimate distance modulus (mag) |
| `distance_modulus_err` | float | Uncertainty on distance modulus (mag) |
| `distance_mpc` | float | Distance in Mpc (derived from distance modulus) |
| `dm_sn_ia` | float | Distance modulus from Type Ia supernovae |
| `dm_sn_ia_err` | float | Uncertainty on SNe Ia distance modulus |
| `dm_tully_fisher` | float | Distance modulus from Tully-Fisher relation |
| `dm_tully_fisher_err` | float | Uncertainty on Tully-Fisher distance modulus |
| `dm_fundamental_plane` | float | Distance modulus from fundamental plane |
| `dm_fundamental_plane_err` | float | Uncertainty on fundamental plane DM |
| `dm_surface_brightness` | float | Distance modulus from surface brightness fluctuations |
| `dm_surface_brightness_err` | float | Uncertainty on SBF distance modulus |
| `dm_sn_ii` | float | Distance modulus from Type II supernovae |
| `dm_sn_ii_err` | float | Uncertainty on SNe II distance modulus |
| `dm_trgb` | float | Distance modulus from tip of red giant branch |
| `dm_trgb_err` | float | Uncertainty on TRGB distance modulus |
| `dm_cepheid` | float | Distance modulus from Cepheid variables |
| `dm_cepheid_err` | float | Uncertainty on Cepheid distance modulus |
| `dm_maser` | float | Distance modulus from maser observations |
| `dm_maser_err` | float | Uncertainty on maser distance modulus |
| `ra_deg` | float | Right ascension J2000 (degrees) |
| `dec_deg` | float | Declination J2000 (degrees) |
| `glon_deg` | float | Galactic longitude (degrees) |
| `glat_deg` | float | Galactic latitude (degrees) |
| `sgl_deg` | float | Supergalactic longitude (degrees) |
| `sgb_deg` | float | Supergalactic latitude (degrees) |
| `in_cf3` | bool | Present in Cosmicflows-3 catalog |

## Quick stats

- **55,877** galaxy distance measurements
- **12,222** with Tully-Fisher distances
- **42,223** with fundamental plane distances
- **1,004** with Type Ia supernova distances
- **446** with TRGB distances
- **69** with Cepheid distances
- **15,839** also in Cosmicflows-3
- Median distance: **203.8 Mpc**

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/cosmicflows-galaxy-distances", split="train")
df = ds.to_pandas()

# Galaxies within 100 Mpc (local universe)
local = df[df["distance_mpc"] <= 100]
print(f"{len(local):,} galaxies within 100 Mpc")

# Galaxies with Cepheid-calibrated distances
cepheids = df[df["dm_cepheid"].notna()]
print(f"{len(cepheids):,} with Cepheid distances")

# Sky distribution in supergalactic coordinates
import matplotlib.pyplot as plt
plt.scatter(df["sgl_deg"], df["sgb_deg"], s=0.2, alpha=0.3, c=df["distance_mpc"],
cmap="viridis", vmax=200)
plt.colorbar(label="Distance (Mpc)")
plt.xlabel("Supergalactic Longitude")
plt.ylabel("Supergalactic Latitude")
plt.title("Cosmicflows-4: Galaxy Distance Map")
```

## Data source

[Cosmicflows-4](https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/ApJ/944/94)
(Tully R.B., Kourkchi E., Courtois H.M., et al., 2023, ApJ, 944, 94),
accessed via [VizieR](https://vizier.cds.unistra.fr/), CDS Strasbourg.

## Update schedule

Static dataset (fixed catalog release). No scheduled updates.

## Related datasets

- [messier-catalog](https://huggingface.co/datasets/juliensimon/messier-catalog) -- Messier deep-sky objects
- [ngc-ic-catalog](https://huggingface.co/datasets/juliensimon/ngc-ic-catalog) -- NGC/IC deep-sky catalog
- [exoplanet-catalog](https://huggingface.co/datasets/juliensimon/exoplanet-catalog) -- NASA Exoplanet Archive

## Pipeline

Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## Citation

```bibtex
@dataset{cosmicflows_galaxy_distances,
author = {Simon, Julien},
title = {Cosmicflows-4 Galaxy Distances},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/cosmicflows-galaxy-distances},
note = {Based on Cosmicflows-4 (Tully et al. 2023, ApJ, 944, 94) via VizieR CDS Strasbourg}
}
```

## License

[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)

---
license: CC-BY-4.0
pretty_name: "Cosmicflows-4 星系距离数据集"
language:
- en
description: "Cosmicflows-4 星系距离星表：包含8种独立方法得到的55877条星系距离测量结果，分别为Tully-Fisher关系（Tully-Fisher）、Ia型超新星（SNe Ia）、基本平面（fundamental plane）、红巨星分支端点（TRGB）、造父变星（Cepheids）、脉泽（masers）、II型超新星（SNe II）以及表面亮度涨落（SBF）。数据源自斯特拉斯堡CDS的VizieR数据库（VizieR CDS Strasbourg）。"
task_categories:
- 表格分类
tags:
- 太空
- 星系
- 距离
- 宇宙学
- 天文学
- 开放数据
- 表格数据
size_categories:
- 10000 < 样本数 < 100000
configs:
- config_name: 默认配置
data_files:
- split: 训练集
path: data/cosmicflows_galaxy_distances.parquet
default: true
---

# Cosmicflows-4 星系距离数据集

*隶属于Hugging Face平台的[Astronomy Datasets](https://huggingface.co/collections/juliensimon/astronomy-datasets-69c24caf2f17e36128946743)数据集合集。*

Cosmicflows-4（简称CF4）星表是迄今最全面的星系距离汇编数据集。由Tully等人于2023年发表，该数据集包含8种独立方法得到的**55877条**星系距离测量结果，可用于研究宇宙距离阶梯、大尺度结构以及星系本动速度。

## 数据集描述

星系距离是宇宙学研究的核心基础。与红移不同，红移会将哈勃流（Hubble flow）与本动速度（peculiar velocities）混为一谈，而直接距离测量能够让我们绘制出物质真实的三维分布图景。CF4整合了来自以下8种途径的星系距离数据：Ia型超新星（Type Ia supernovae）、Tully-Fisher关系（Tully-Fisher relation）、基本平面（fundamental plane）、红巨星分支端点（tip of the red giant branch, TRGB）、造父变星周光关系（Cepheid period-luminosity）、表面亮度涨落（surface brightness fluctuations, SBF）、II型超新星（Type II supernovae）以及脉泽观测（maser observations）。

每条数据条目均包含PGC星系编号（PGC galaxy identifier）、坐标（赤道坐标、银道坐标、超银道坐标）、CMB坐标系（CMB-frame）下的速度、最优估计的距离模数，以及可获取的各独立方法对应的距离模数。

## 数据字段说明

| 字段名 | 数据类型 | 描述 |
|--------|------|-------------|
| `pgc` | int | PGC星系编号 |
| `pgc_primary` | int | 主PGC编号（用于成组星系） |
| `morphological_type` | float | 形态类型编码（德沃库勒尔T型） |
| `velocity_cmb` | float | CMB坐标系下的速度（单位：km/s） |
| `distance_modulus` | float | 最优估计距离模数（单位：星等，mag） |
| `distance_modulus_err` | float | 距离模数的不确定度（单位：星等） |
| `distance_mpc` | float | 距离（单位：百万秒差距，Mpc，由距离模数推导得到） |
| `dm_sn_ia` | float | Ia型超新星距离模数 |
| `dm_sn_ia_err` | float | Ia型超新星距离模数的不确定度 |
| `dm_tully_fisher` | float | Tully-Fisher关系距离模数 |
| `dm_tully_fisher_err` | float | Tully-Fisher关系距离模数的不确定度 |
| `dm_fundamental_plane` | float | 基本平面距离模数 |
| `dm_fundamental_plane_err` | float | 基本平面距离模数的不确定度 |
| `dm_surface_brightness` | float | 表面亮度涨落距离模数 |
| `dm_surface_brightness_err` | float | 表面亮度涨落距离模数的不确定度 |
| `dm_sn_ii` | float | II型超新星距离模数 |
| `dm_sn_ii_err` | float | II型超新星距离模数的不确定度 |
| `dm_trgb` | float | 红巨星分支端点距离模数 |
| `dm_trgb_err` | float | 红巨星分支端点距离模数的不确定度 |
| `dm_cepheid` | float | 造父变星距离模数 |
| `dm_cepheid_err` | float | 造父变星距离模数的不确定度 |
| `dm_maser` | float | 脉泽观测距离模数 |
| `dm_maser_err` | float | 脉泽观测距离模数的不确定度 |
| `ra_deg` | float | J2000坐标系赤经（单位：度） |
| `dec_deg` | float | J2000坐标系赤纬（单位：度） |
| `glon_deg` | float | 银道经度（单位：度） |
| `glat_deg` | float | 银道纬度（单位：度） |
| `sgl_deg` | float | 超银道经度（单位：度） |
| `sgb_deg` | float | 超银道纬度（单位：度） |
| `in_cf3` | bool | 是否收录于Cosmicflows-3星表 |

## 快速统计数据

- **55877条**星系距离测量结果
- **12222条**带有Tully-Fisher关系距离测量结果
- **42223条**带有基本平面距离测量结果
- **1004条**带有Ia型超新星距离测量结果
- **446条**带有红巨星分支端点距离测量结果
- **69条**带有造父变星距离测量结果
- **15839条**同时收录于Cosmicflows-3星表
- 距离中位数：**203.8 百万秒差距（Mpc）**

## 使用示例

python
from datasets import load_dataset

ds = load_dataset("juliensimon/cosmicflows-galaxy-distances", split="train")
df = ds.to_pandas()

# 筛选100百万秒差距内的星系（本地宇宙）
local = df[df["distance_mpc"] <= 100]
print(f"{len(local):,} 个星系位于100 Mpc范围内")

# 筛选带有造父变星校准距离的星系
cepheids = df[df["dm_cepheid"].notna()]
print(f"{len(cepheids):,} 个星系带有造父变星距离测量结果")

# 绘制超银道坐标系下的天区分布
import matplotlib.pyplot as plt
plt.scatter(df["sgl_deg"], df["sgb_deg"], s=0.2, alpha=0.3, c=df["distance_mpc"], cmap="viridis", vmax=200)
plt.colorbar(label="距离（Mpc）")
plt.xlabel("超银道经度")
plt.ylabel("超银道纬度")
plt.title("Cosmicflows-4：星系距离分布图")

## 数据来源

[Cosmicflows-4](https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/ApJ/944/94)
（Tully R.B.、Kourkchi E.、Courtois H.M.等，2023，《天体物理学杂志》，第944卷，第94页），数据通过[VizieR](https://vizier.cds.unistra.fr/)获取，源自斯特拉斯堡CDS数据库。

## 更新计划

静态数据集（固定版本星表），无更新计划。

## 相关数据集

- [messier-catalog](https://huggingface.co/datasets/juliensimon/messier-catalog) —— 梅西耶深空天体数据集
- [ngc-ic-catalog](https://huggingface.co/datasets/juliensimon/ngc-ic-catalog) —— NGC/IC深空天体星表
- [exoplanet-catalog](https://huggingface.co/datasets/juliensimon/exoplanet-catalog) —— 美国国家航空航天局系外行星档案数据集

## 数据处理流程

源代码：[juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## 引用格式

bibtex
@dataset{cosmicflows_galaxy_distances,
author = {Simon, Julien},
title = {Cosmicflows-4 Galaxy Distances},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/cosmicflows-galaxy-distances},
note = {基于Cosmicflows-4数据集（Tully等，2023，ApJ，944，94），通过VizieR CDS斯特拉斯堡数据库获取}
}

## 许可证

[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)