---
license: cc-by-4.0
pretty_name: "Fermi LAT Third Catalog of Hard Sources (3FHL)"
language:
  - en
description: "1,556 gamma-ray sources detected above 10 GeV by Fermi LAT over 7 years, bridging the GeV-TeV energy gap."
task_categories:
  - tabular-classification
tags:
  - space
  - gamma-ray
  - fermi
  - nasa
  - tev
  - high-energy
  - astronomy
  - open-data
  - tabular-data
size_categories:
  - 1K<n<10K
configs:
  - config_name: default
    data_files:
      - split: train
        path: data/fermi-3fhl.parquet
    default: true
---

# Fermi LAT Third Catalog of Hard Sources (3FHL)

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

Gamma-ray sources detected above 10 GeV by the Fermi Large Area Telescope (LAT)
over 7 years of observation. Currently **1,558** sources with 67 attributes each.

## Dataset description

The 3FHL catalog (Ajello et al. 2017) contains sources detected by Fermi LAT in the
10 GeV - 2 TeV energy range using 7 years of Pass 8 data. This catalog bridges the gap
between the GeV regime covered by the standard Fermi catalogs and the TeV regime
covered by ground-based Cherenkov telescopes (H.E.S.S., MAGIC, VERITAS).

Sources include blazars, pulsar wind nebulae, supernova remnants, and unidentified
gamma-ray emitters. The catalog is essential for planning observations with current
and future TeV observatories like CTA.

## Quick stats

- **1,558** gamma-ray sources above 10 GeV

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/fermi-3fhl-hard-gamma-ray", split="train")
df = ds.to_pandas()

# Highest significance sources
print(df.head(10)[["name", "ra", "dec"]])

# Sky map
import matplotlib.pyplot as plt
plt.figure(figsize=(12, 6))
plt.scatter(df["ra"], df["dec"], s=2, alpha=0.5)
plt.xlabel("RA (deg)")
plt.ylabel("Dec (deg)")
plt.title("Fermi 3FHL Sources (>10 GeV)")
plt.gca().invert_xaxis()
```

## Data source

All data comes from the [Fermi 3FHL Catalog](https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermi3fhl.html)
hosted by NASA's High Energy Astrophysics Science Archive Research Center (HEASARC),
accessed via the TAP protocol.

Reference: Ajello, M. et al. 2017, ApJS, 232, 18.

## Related datasets

- [gamma-ray-bursts](https://huggingface.co/datasets/juliensimon/gamma-ray-bursts) — Fermi GBM Gamma-Ray Burst Catalog
- [pulsar-catalog](https://huggingface.co/datasets/juliensimon/pulsar-catalog) — ATNF Pulsar Catalogue

## Pipeline

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

## Citation

```bibtex
@dataset{fermi_3fhl,
  author = {Simon, Julien},
  title = {Fermi LAT Third Catalog of Hard Sources (3FHL)},
  year = {2026},
  publisher = {Hugging Face},
  url = {https://huggingface.co/datasets/juliensimon/fermi-3fhl-hard-gamma-ray},
  note = {Based on Fermi 3FHL (Ajello et al. 2017) via NASA HEASARC}
}
```

## License

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