juliensimon/iue-observations

---
license: cc-by-4.0
pretty_name: "IUE Observation Catalog"
language:
- en
description: "The IUE Observation Catalog indexes every spectrum obtained by the International Ultraviolet Explorer (IUE), a joint NASA/ESA/UK mission that operated from January 26, 1978 to September 30, 1996 — 18."
task_categories:
- tabular-classification
tags:
- space
- iue
- nasa
- esa
- ultraviolet
- uv
- spectroscopy
- astronomy
- telescope
- open-data
- tabular-data
- parquet
size_categories:
- 100K<n<1M
configs:
- config_name: default
data_files:
- split: train
path: data/iue_observations.parquet
default: true
---

# IUE Observation Catalog

<div align="center">
<img src="banner.jpg" alt="UV-bright sky — representative of the ultraviolet sky that IUE surveyed for nearly two decades" width="400">
<p><em>Credit: NASA/GSFC</em></p>
</div>

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

## Dataset description

The IUE Observation Catalog indexes every spectrum obtained by the International Ultraviolet Explorer (IUE), a joint NASA/ESA/UK mission that operated from January 26, 1978 to September 30, 1996 — 18.7 years, a record for a UV space observatory. IUE orbited in a geosynchronous orbit at ~36,000 km altitude, allowing 24-hour observation from a ground station in Maryland (NASA) and another in Villafranca (ESA). Its 45-cm Ritchey–Chrétien telescope fed echelle spectrographs in three cameras: SWP (Short Wave Prime, 1150–2000 Å), LWP (Long Wave Prime, 2000–3200 Å), and LWR (Long Wave Redundant, same range as LWP; operated until a 1983 failure).

Each row is one IUE spectrum — over 100,000 pointings across nearly two decades. Targets span every UV-interesting astronomical object class: bright OB stars, symbiotic binaries, supernovae (IUE watched SN 1987A live), Seyfert galaxies and quasars (including the famous 3C 273 and NGC 4151 monitoring programs visible in this table), protoplanetary nebulae, comets, planets, and solar-system moons. Because IUE's archive is so long, it remains the go-to source for UV variability studies on timescales from days to decades.

This dataset is the canonical catalog of what IUE observed, useful for historical cross-matching (finding the IUE coverage of any source that became interesting later), for UV variability archaeology (many active galactic nuclei and cataclysmic variables have IUE baselines nowhere else in the archive), and for teaching (IUE calibration data and well-studied objects like η Carinae are included in many astronomy curricula). It complements the HST, GALEX, JWST, and Chandra observation catalogs in this collection.

The catalog is derived from MAST's CAOM table `dbo.caomobservation` (collection = 'IUE'). The IUE archive is static since 1996; this dataset refreshes quarterly to pick up any late reprocessing or metadata fixes.

This dataset is suitable for **tabular classification** tasks.

## Schema

| Column | Type | Description | Sample | Null % |
|--------|------|-------------|--------|--------|
| `obs_id` | string | IUE image identifier (e.g., 'lwp00501'); camera prefix followed by a 5-digit exposure number. Primary key. | lwp00501 | 0.0% |
| `obstype` | string | CAOM observation type: 'S' (simple single spectrum) or 'C' (composite) | S | 0.0% |
| `intent` | string | Observation intent: 'science' or 'calibration' | science | 0.0% |
| `proposal_id` | string | IUE observing proposal identifier (mixed-case alphanumeric, e.g., 'KQ120') | CSGAD | 0.4% |
| `proposal_pi` | string | Principal Investigator name (free-form; no canonical format) | Andrea K. Dupree | 1.1% |
| `target_name` | string | Target name as provided by the proposer — catalog designations, common names, or coordinates | HD 39801 | 0.0% |
| `target_ra` | float64 | Target right ascension in decimal degrees (ICRS) | 88.79343677872521 | 0.0% |
| `target_dec` | float64 | Target declination in decimal degrees (ICRS) | 7.40691081428178 | 0.0% |
| `camera` | string | IUE camera code: LWP, LWR, or SWP (see `camera_name` for expansion) | LWP | 0.0% |
| `exposure_number` | Int64 | Sequential exposure number within the camera's archive (1–many thousands) | 501 | 0.0% |
| `camera_name` | string | Human-readable camera name with wavelength range | Long Wave Prime (2000–3200 Å, primary) | 0.0% |

## Quick stats

- **101,971** IUE spectra (1978–1996)
- Cameras: **SWP** (54,259), **LWP** (30,727), **LWR** (16,985)
- **15,478** distinct target names
- **5,141** distinct observing proposals

## Usage

```python
from datasets import load_dataset

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

```python
from datasets import load_dataset

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

# All spectra of 3C 273 (famous quasar with long IUE monitoring)
tres_c_273 = df[df["target_name"].str.contains("3C 273", case=False, na=False)]
print(f"3C 273 spectra: {len(tres_c_273):,}")

# Spectra by camera
import matplotlib.pyplot as plt
df["camera"].value_counts().plot.bar()
plt.ylabel("Spectrum count"); plt.title("IUE exposures by camera (1978–1996)")
plt.show()

# Sky distribution of IUE pointings (sample)
sample = df.sample(min(50000, len(df)))
plt.figure(figsize=(12, 6))
plt.scatter(sample["target_ra"], sample["target_dec"], s=0.3, alpha=0.3)
plt.xlabel("RA (deg)"); plt.ylabel("Dec (deg)")
plt.gca().invert_xaxis()
plt.title("IUE target sky distribution (50K sample)")
plt.show()
```

## Data source

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

## Update schedule

Quarterly (1st of Jan/Apr/Jul/Oct at 15:30 UTC) via [GitHub Actions](https://github.com/juliensimon/space-datasets).

## Related datasets

- [juliensimon/hst-observations](https://huggingface.co/datasets/juliensimon/hst-observations)

- [juliensimon/galex-observations](https://huggingface.co/datasets/juliensimon/galex-observations)

- [juliensimon/jwst-observations](https://huggingface.co/datasets/juliensimon/jwst-observations)

- [juliensimon/chandra-x-ray-sources](https://huggingface.co/datasets/juliensimon/chandra-x-ray-sources)

- [juliensimon/quasar-catalog](https://huggingface.co/datasets/juliensimon/quasar-catalog)

> If you find this dataset useful, please consider [giving it a like](https://huggingface.co/datasets/juliensimon/iue-observations) on Hugging Face. It helps others discover it.

## About the author

Created by [Julien Simon](https://julien.org) — AI Operating Partner at Fortino Capital. Part of the [Space Datasets](https://julien.org/datasets) collection.

## Citation

```bibtex
@dataset{iue_observations,
title = {IUE Observation Catalog},
author = {juliensimon},
year = {2026},
url = {https://huggingface.co/datasets/juliensimon/iue-observations},
publisher = {Hugging Face}
}
```

## License

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