GalaxiesML: an imaging and photometric dataset of galaxies for machine learning

# GalaxiesML README

Version 6.1

## Overview

GalaxiesML is a machine learning-ready dataset of galaxy images, photometry, redshifts, and structural parameters. It is designed for machine learning applications in astrophysics, particularly for tasks such as redshift estimation and galaxy morphology classification. The dataset comprises **286,401 galaxy images** from the Hyper-Suprime-Cam (HSC) Survey PDR2 in five filters: g, r, i, z, y, with spectroscopically confirmed redshifts as ground truth.

This dataset is particularly useful for developing machine learning models for upcoming large-scale surveys like **LSST** and **Euclid**.

## Features

- **286,401 galaxy images** in five photometric bands (g, r, i, z, y).

- Spectroscopic redshifts for each galaxy, with redshift values ranging from **0.01 to 4**.

- Morphological parameters derived from galaxy images, including **Sérsic index**, **half-light radius**, and **ellipticity**.

- **Machine learning-friendly formats**: images are provided in **HDF5** format, along with CSV metadata.

## Examples of Using GalaxiesML

Examples of uses of GalaxiesML are outlined in Do et al. (2024). The repository for example code are here:

https://github.com/astrodatalab/galaxiesml_examples

## Citation

Please cite the following papers if you use this dataset in your work:

1. **GalaxiesML Dataset**:

Do, T. et al., *GalaxiesML: A Dataset of Galaxy Images, Photometry, Redshifts, and Structural Parameters for Machine Learning*. arXiv:2410.00271, https://arxiv.org/abs/2410.00271 (2024)

2. **Hyper Suprime-Cam Subaru Strategic Program (HSC PDR2)**:

- Aihara, H., et al., *Second Data Release of the Hyper Suprime-Cam Subaru Strategic Program*. Publications of the Astronomical Society of Japan, 71(6), 114 (2019). DOI: [10.1093/pasj/psz103](https://doi.org/10.1093/pasj/psz103)

3. **Spectroscopic Surveys**:

- Several publicly available spectroscopic redshift catalogs were used in creating this dataset. Notable sources include:

- **zCOSMOS Survey**: Lilly, S. J., et al., *The zCOSMOS 10k-Bright Spectroscopic Sample*. The Astrophysical Journal Supplement Series, 184(2), 218-229 (2009). DOI: [10.1088/0067-0049/184/2/218](https://doi.org/10.1088/0067-0049/184/2/218)

- **VIMOS Public Extragalactic Survey (VIPERS)**: Garilli, B., et al., *The VIMOS Public Extragalactic Survey (VIPERS): First Data Release of 57,204 Spectroscopic Measurements*. Astronomy & Astrophysics, 562, A23 (2014). DOI: [10.1051/0004-6361/201322790](https://doi.org/10.1051/0004-6361/201322790)

- **DEEP2 Survey**: Newman, J. A., et al., *The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts*. The Astrophysical Journal Supplement Series, 208(1), 5 (2013). DOI: [10.1088/0067-0049/208/1/5](https://doi.org/10.1088/0067-0049/208/1/5)

## How to Access

The dataset is publicly available on **Zenodo** with the DOI: **[10.5281/zenodo.11117528](https://doi.org/10.5281/zenodo.11117528)**.

## License

This dataset is licensed under a **Creative Commons Attribution 4.0 International License (CC BY 4.0)**. You are free to share and adapt the dataset as long as appropriate credit is given. For more details, visit: **[CC BY 4.0 License](https://creativecommons.org/licenses/by/4.0/)**.

Please cite the references mentioned above if you use this dataset in your work.