juliensimon/galex-observations

GALEX Observation Catalog

Credit: NASA/JPL-Caltech

Part of a dataset collection on Hugging Face.

Dataset description

The GALEX Observation Catalog indexes every pointing observed by NASA's Galaxy Evolution Explorer (GALEX) mission between its launch on April 28, 2003 and the end of operations in June 2013. GALEX was a dedicated ultraviolet space telescope with a 50-cm primary mirror, imaging the sky simultaneously in two bands: Far-UV (FUV, 1350–1750 Å) and Near-UV (NUV, 1750–2750 Å). Its 1.2-degree circular field of view and low-noise microchannel-plate detectors enabled the first comprehensive UV all-sky survey, mapping over 60,000 square degrees and cataloguing hundreds of millions of UV sources.

Each row in this catalog is one GALEX observation, tagged with its survey origin. The surveys include AIS (All-sky Imaging Survey — shallow, wide), MIS (Medium Imaging Survey — overlapping SDSS), DIS (Deep Imaging Survey — deepest UV field survey to date), NGS (Nearby Galaxy Survey), and specialised Guest Investigator, calibration, and spectroscopic programs. Field centres are in ICRS RA/Dec degrees, and the target_name captures the proposer-assigned identifier for each tile.

This dataset is designed for cross-matching UV sources with catalogs at other wavelengths (optical Gaia/SDSS/Pan-STARRS, infrared WISE, X-ray Chandra/eROSITA), for stellar population studies (UV is a tracer of young star formation), for AGN selection (UV-bright galaxies and quasars), and for planning deep archival follow-up. It complements the Hubble, JWST, Chandra, and eROSITA observation catalogs in this collection, extending the multi-wavelength view into the UV.

The catalog is derived from MAST's CAOM table dbo.caomobservation (collection = 'GALEX'). The GALEX archive is static since 2013, so this dataset is refreshed quarterly for any late reprocessing.

This dataset is suitable for tabular classification tasks.

Schema

Column	Type	Description	Sample	Null %
obs_id	string	MAST observation identifier for this GALEX observation (opaque numeric string). Primary key.	2391589523080347648	0.0%
obstype	string	CAOM observation type code: 'S' (simple single exposure) or 'C' (composite, e.g. a co-added tile)	S	0.0%
intent	string	Observation intent: 'science' (survey pointing) or 'calibration'	science	0.0%
survey_code	string	GALEX survey code: AIS, MIS, DIS, NGS, GII, GIS, CAI, CAS, MSS, DSS, WSS, ETS. See survey_name for expansion.	NGS	0.0%
target_name	string	Target field identifier, often encoding the pointing or an associated catalog source	NGA_NGC5398_580_F5_19_158	0.0%
target_ra	float64	Field centre right ascension in decimal degrees (ICRS)	210.54223247715905	0.0%
target_dec	float64	Field centre declination in decimal degrees (ICRS)	-32.6804067553693	0.0%
survey_name	string	Human-readable survey name (e.g. 'All-sky Imaging Survey' for AIS)	Nearby Galaxy Survey	0.0%

Quick stats

• 274,911 GALEX observations (2003–2013)
• 274,911 science, 0 calibration
• Top surveys: AIS (98,660), GIS (87,226), MIS (18,089), ETS (17,225), CAS (10,991)

Usage

from datasets import load_dataset

ds = load_dataset("juliensimon/galex-observations", split="train")
df = ds.to_pandas()

from datasets import load_dataset

ds = load_dataset("juliensimon/galex-observations", split="train")
df = ds.to_pandas()

# Deep survey fields only
deep = df[df["survey_code"] == "DIS"]
print(f"Deep Imaging Survey pointings: {len(deep):,}")

# UV sky coverage map (All-sky Imaging Survey)
import matplotlib.pyplot as plt
ais = df[df["survey_code"] == "AIS"]
plt.figure(figsize=(12, 6))
plt.scatter(ais["target_ra"], ais["target_dec"], s=0.3, alpha=0.3)
plt.xlabel("RA (deg)"); plt.ylabel("Dec (deg)")
plt.gca().invert_xaxis()
plt.title("GALEX All-sky Imaging Survey (AIS) pointings")
plt.show()

# Observations per survey
df["survey_code"].value_counts().plot.bar()
plt.ylabel("Observation count")
plt.title("GALEX observations by survey program")
plt.show()

Data source

https://archive.stsci.edu/missions-and-data/galex

Update schedule

Quarterly (1st of Jan/Apr/Jul/Oct at 14:30 UTC) via GitHub Actions.

Related datasets

• juliensimon/gswlc-galaxy-properties

• juliensimon/hst-observations

• juliensimon/jwst-observations

• juliensimon/chandra-x-ray-sources

• juliensimon/nasa-exoplanets

If you find this dataset useful, please consider giving it a like on Hugging Face. It helps others discover it.

About the author

Created by Julien Simon — AI Operating Partner at Fortino Capital. Part of the Space Datasets collection.

Citation

@dataset{galex_observations,
  title = {GALEX Observation Catalog},
  author = {juliensimon},
  year = {2026},
  url = {https://huggingface.co/datasets/juliensimon/galex-observations},
  publisher = {Hugging Face}
}

License

CC-BY-4.0