---
title: "UKIRT-2017-BLG-001L b"
url: "https://spacecatalog.org/object/ukirt-2017-blg-001l-b"
release: "DR1"
licence: "No licence stated; acknowledgement requested"
citation: "SpaceCatalog. UKIRT-2017-BLG-001L b [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ukirt-2017-blg-001l-b"
---

# UKIRT-2017-BLG-001L b

UKIRT-2017-BLG-001L b is a gas giant in the constellation [Sagittarius](https://spacecatalog.org/constellation/sagittarius), 20 548 ly from Earth. It orbits UKIRT-2017-BLG-001L at a mean distance of 4.18 AU. It has a mass of 1.28 M♃ and an estimated radius of 1.22 R♃ · 87 380 km. The radius is an estimate from the mass rather than a measurement. It was discovered in 2018.

## At a glance

- **WHAT IT IS:** Gas giant
- **HOW FAR:** 20 548 ly — The light arriving now left it that long ago.
- **HOW BIG:** 1.22 R♃ · 87 380 km — Its radius: half the width across.
- **WHERE TO LOOK:** [Sagittarius](https://spacecatalog.org/constellation/sagittarius) — The patch of sky it sits in, as seen from Earth.

## Properties

| Quantity | Value |
| --- | --- |
| CLASS | Gas giant |
| MASS | 1.28 M♃ +0.38 / −0.44 |
| RADIUS | 1.22 R♃ · 87 380 km — estimated from the mass, not measured |
| DISTANCE FROM EARTH | 20 548 ly +5219 / −6849 — by NASA Exoplanet Archive sy\_dist (Shvartzvald+ 2018, 2018ApJ...857L...8S) |
| ORBITS | UKIRT-2017-BLG-001L |
| SEMI-MAJOR AXIS | 4.18 AU +0.96 / −0.88 |
| CONSTELLATION | Sagittarius |
| RIGHT ASCENSION (J2000) | 17h 46m 37.0s |
| DECLINATION (J2000) | −29° 12′ 40.9″ |
| DISCOVERED | 2018 |

## Catalogue data

### WHAT KIND OF THING IT IS

What the object is in itself, rather than how it happens to look from here.

| Field | Value |
| --- | --- |
| Host star mass | 0.81 +0.21 / −0.27 M☉ |

### THE ORBIT

The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.

| Field | Value |
| --- | --- |
| Host star | UKIRT-2017-BLG-001L |
| Stars in system | 1 |
| Planets in system | 1 |

### WHEN IT WAS FOUND

Who first saw it, from where, and by what method.

| Field | Value |
| --- | --- |
| Discovery method | Microlensing |
| Discovered at | Mauna Kea Observatory |

## Also known as

- Exoplanet: UKIRT-2017-BLG-001L b
- Host star: UKIRT-2017-BLG-001L

## Source

[NASA Exoplanet Archive (Planetary Systems Composite Parameters)](https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=PSCompPars) — No licence stated; acknowledgement requested

The producer asks: This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Cite Christiansen et al. (2025), Planetary Science Journal (doi:10.3847/PSJ/ade3c2), and the literature reference given with each value.

How this was made: https://spacecatalog.org/methods#source-exoplanet-archive

## Cite this page

SpaceCatalog. UKIRT-2017-BLG-001L b \[catalogue entry\]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/ukirt-2017-blg-001l-b

```bibtex
@misc{spacecatalog_ukirt-2017-blg-001l-b,
  author       = {{SpaceCatalog}},
  title        = {{UKIRT-2017-BLG-001L b}},
  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
  year         = {2026},
  url          = {https://spacecatalog.org/object/ukirt-2017-blg-001l-b},
  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from NASA Exoplanet Archive (Planetary Systems Composite Parameters).}
}
```

NASA Exoplanet Archive (Planetary Systems Composite Parameters) — No licence stated; acknowledgement requested

Acknowledgement the producer asks for: This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Cite Christiansen et al. (2025), Planetary Science Journal (doi:10.3847/PSJ/ade3c2), and the literature reference given with each value.

The page itself, with its pictures, the sky map and the observing tools: https://spacecatalog.org/object/ukirt-2017-blg-001l-b