---
license: cc-by-4.0
pretty_name: "Pantheon+ Type Ia Supernovae"
language:
  - en
description: "Gold standard cosmological dataset: 1,701 spectroscopically confirmed Type Ia supernovae from Pantheon+ used to measure H0 and dark energy."
task_categories:
  - tabular-regression
tags:
  - space
  - supernova
  - cosmology
  - hubble-constant
  - dark-energy
  - pantheon
  - open-data
size_categories:
  - 1K<n<10K
---

# Pantheon+ Type Ia Supernovae

The gold standard cosmological dataset -- **1,701** spectroscopically confirmed Type Ia supernovae
from the Pantheon+ analysis, used to measure the Hubble constant (H0) and constrain the dark energy
equation of state. This is the dataset behind the "Hubble tension" debate.

## Dataset description

Pantheon+ combines supernova light curves from 20 surveys spanning redshifts
0.0012 to 2.261. Each SN Ia is standardized using the SALT2 light-curve fitter,
providing stretch (x1) and color (c) parameters that transform raw apparent magnitudes into
calibrated distance moduli. Combined with Cepheid-calibrated distances from SH0ES, this
dataset yields the most precise local measurement of the Hubble constant.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `sn_name` | string | Supernova identifier (CID) |
| `survey_id` | int64 | Survey identifier |
| `redshift_hd` | float64 | Hubble-diagram redshift (peculiar velocity corrected) |
| `redshift_hd_err` | float64 | Hubble-diagram redshift uncertainty |
| `redshift_cmb` | float64 | CMB-frame redshift |
| `redshift_cmb_err` | float64 | CMB-frame redshift uncertainty |
| `redshift_helio` | float64 | Heliocentric redshift |
| `redshift_helio_err` | float64 | Heliocentric redshift uncertainty |
| `apparent_mag_b` | float64 | Apparent B-band magnitude (SALT2 mB) |
| `apparent_mag_b_err` | float64 | Apparent magnitude uncertainty |
| `stretch_x1` | float64 | SALT2 stretch parameter x1 |
| `stretch_x1_err` | float64 | Stretch uncertainty |
| `color_c` | float64 | SALT2 color parameter c |
| `color_c_err` | float64 | Color uncertainty |
| `host_log_mass` | float64 | Host galaxy log stellar mass (solar masses) |
| `host_log_mass_err` | float64 | Host mass uncertainty |
| `fit_probability` | float64 | SALT2 fit probability |
| `distance_modulus` | float64 | Distance modulus from SH0ES analysis |
| `distance_modulus_err` | float64 | Distance modulus diagonal uncertainty |

## Quick stats

- **1,701** Type Ia supernovae from **20** surveys
- Redshift range: 0.0012 to 2.261 (median 0.164)
- Distance modulus range: 29.00 to 46.18 mag

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/pantheon-plus-sne-ia", split="train")
df = ds.to_pandas()

# Hubble diagram
import matplotlib.pyplot as plt
import numpy as np

valid = df[df["distance_modulus"] > 0]
plt.errorbar(valid["redshift_cmb"], valid["distance_modulus"],
             yerr=valid["distance_modulus_err"],
             fmt=".", ms=2, alpha=0.5, elinewidth=0.5)
plt.xscale("log")
plt.xlabel("Redshift (CMB frame)")
plt.ylabel("Distance modulus (mag)")
plt.title("Pantheon+ Hubble Diagram")
plt.show()

# Color-stretch distribution
plt.scatter(df["stretch_x1"], df["color_c"], s=2, alpha=0.3)
plt.xlabel("Stretch x1")
plt.ylabel("Color c")
plt.title("SALT2 Parameter Distribution")
plt.show()

# Redshift distribution
df["redshift_cmb"].hist(bins=50)
plt.xlabel("Redshift")
plt.ylabel("Count")
plt.title("Pantheon+ Redshift Distribution")
plt.show()
```

## Data source

Scolnic, D., et al. (2022), *The Pantheon+ Analysis: The Full Dataset and Light-curve Release.*
Astrophysical Journal, 938, 113.

Brout, D., et al. (2022), *The Pantheon+ Analysis: Cosmological Constraints.*
Astrophysical Journal, 938, 110.

Data release: [PantheonPlusSH0ES/DataRelease](https://github.com/PantheonPlusSH0ES/DataRelease)

## Pipeline

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

## Citation

```bibtex
@dataset{pantheon_plus_sne,
  author = {Simon, Julien},
  title = {Pantheon+ Type Ia Supernovae},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/pantheon-plus-sne-ia},
  note = {Based on Scolnic et al. (2022) and Brout et al. (2022) Pantheon+ data release}
}
```

## License

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