---
title: "HN Boo"
url: "https://spacecatalog.org/object/hd-128311"
release: "DR1"
licence: "CC-BY-SA-4.0"
citation: "SpaceCatalog. HN Boo [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-128311"
---

# HN Boo

HN Boo is a K3V orange dwarf in the constellation [Boötes](https://spacecatalog.org/constellation/bootes), 53.82 ly from Earth, shining at apparent magnitude 7.48 (V). Other catalogues list it as GJ 3860, HD 128311 and HIP 71395.

## At a glance

- **WHAT IT IS:** Orange dwarf
- **HOW FAR:** 53.82 ly — The light arriving now left it that long ago.
- **HOW BRIGHT (V):** 7.48 — Binoculars reach it; the naked eye does not.
- **WHERE TO LOOK:** [Boötes](https://spacecatalog.org/constellation/bootes) — The patch of sky it sits in, as seen from Earth.

## Properties

| Quantity | Value |
| --- | --- |
| CLASS | K3V orange dwarf |
| MASS | 0.78 M☉ — Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) |
| DISTANCE FROM EARTH | 53.82 ly — by parallax |
| APPARENT MAGNITUDE (V) | 7.48 |
| ABSOLUTE MAGNITUDE (V) | 6.39 |
| CONSTELLATION | Boötes |
| RIGHT ASCENSION (J2000) | 14h 36m 00.6s |
| DECLINATION (J2000) | +09° 44′ 47.5″ |

## 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 |
| --- | --- |
| Spectral type | K3V |
| Surface temperature | 4760 K |
| Luminosity | 0.241657 L☉ |
| Luminosity (bolometric) | 0.3037 L☉ |
| Radius | 0.813 R☉ |
| Mass | 0.779 M☉ |
| Surface gravity (log g) | 4.518 |
| Metallicity (\[Fe/H\]) | 0.05 ±0.072 |
| Age | 1.03×10¹⁰ years |
| Variability | BY Draconis spotted rotating variable |
| Variability type (GCVS) | BY |
| Variability period | 11.54 days |

### HOW BRIGHT IT IS

What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.

| Field | Value |
| --- | --- |
| Colour index (B−V) | 0.973 |
| Variable magnitude, brightest | 7.46 |
| Variable magnitude, faintest | 7.50 |

### WHERE IT IS AND HOW IT MOVES

Position, motion across the sky and the size it covers on it. These are measurements of the object as seen from here, so every one of them depends on where here is.

| Field | Value |
| --- | --- |
| Proper motion (RA) | 205.46 mas/yr |
| Proper motion (Dec) | −249.68 mas/yr |
| Radial velocity | −15 km/s |

### OTHER NAMES AND NUMBERS

The identifiers other catalogues file this object under, for anyone joining this data to theirs.

| Field | Value |
| --- | --- |
| Variable-star designation | HN Boo |

### WHERE THESE FIGURES CAME FROM

Which catalogue, paper or model each of the fields above was read from, where the source named one.

| Field | Value |
| --- | --- |
| Spectral type from | SIMBAD (2010MNRAS.403.1949K, quality C) |
| Stellar parameters from | Gaia DR3 model fit (GSP-Phot, FLAME; RUWE ≤ 1.4) |
| Metallicity from | Median of 14 spectroscopic determinations in 15 papers, compiled from the literature (PASTEL, Soubiran+ 2016); the error bar is the scatter between them |

## Also known as

- Gliese: GJ 3860
- HD: HD 128311
- HIP: HIP 71395
- Variable star: HN Boo

## Source

[HYG Database v4.1](https://github.com/astronexus/HYG-Database) — CC-BY-SA-4.0

The producer asks: HYG Database v4.1, Astronexus (github.com/astronexus/HYG-Database). Fields derived from it stay under CC BY-SA 4.0.

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

## Cite this page

SpaceCatalog. HN Boo \[catalogue entry\]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/hd-128311

```bibtex
@misc{spacecatalog_hd-128311,
  author       = {{SpaceCatalog}},
  title        = {{HN Boo}},
  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
  year         = {2026},
  url          = {https://spacecatalog.org/object/hd-128311},
  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from HYG Database v4.1.}
}
```

HYG Database v4.1 — CC-BY-SA-4.0

Acknowledgement the producer asks for: HYG Database v4.1, Astronexus (github.com/astronexus/HYG-Database). Fields derived from it stay under CC BY-SA 4.0.

The page itself, with its pictures, the sky map and the observing tools: https://spacecatalog.org/object/hd-128311