Ross 128: measured astrometry for the farthest COSMOS stellar landmark

Measured facts

Catalogue identity

Gaia DR3 3796072592206250624

Aliases

FI Virginis · GJ 447

Source id

3796072592206250624

Distance

3.375 pc · 11.01 ly

Measured catalogue

Gaia DR3 (ESA/Gaia/DPAC and the Gaia Archive)

What COSMOS shows

A nearby Gaia source cross-identified by SIMBAD as Ross 128. Its screen marker does not imply a measured stellar diameter or surface appearance.

Being inside the core means it is available immediately rather than streamed from the 25–100 parsec shell, so it is a useful test case for the catalogue’s loading behaviour.

Its screen marker does not imply a measured stellar diameter. Point size is bounded by the renderer and does not encode physical size.

Measured astrometry

Every field below is copied from the shipped Gaia DR3 manifest for the Gaia DR3 high-S/N stellar catalogue inside 100 pc. The catalogue selects sources with parallax S/N of at least 10 and a non-null G magnitude, then stores measured position, colour, motion and the published radial velocity. Naive reciprocal of raw Gaia DR3 parallax for this positive, S/N >= 10 sample. No zero-point correction or Bayesian prior is applied.

Parallax

296.305308 masUncertainty 0.030186 mas; signal-to-noise 9816.1.

Derived distance

3.374897 pc · 11.007 lyNaive reciprocal of the raw positive parallax; no zero-point correction and no Bayesian prior.

Right ascension / declination (ICRS)

176.937688° · 0.799120°Reference epoch J2016.0.

G magnitude

9.6010Used only through the bounded COSMOS brightness transfer, which is not an absolute luminosity estimate.

BP−RP colour index

3.0333Rendered through a restrained display transfer, not converted to a temperature.

Proper motion (μ_α*, μ_δ)

607.299 · -1223.028 mas/yrμ_α* includes the cos δ factor. Positions are propagated linearly from J2016.0.

Radial velocity

Not publishedThe radial component therefore remains unknown and contributes zero only to this short-epoch display approximation.

RUWE

1.082582Gaia renormalised unit weight error, carried as provenance rather than used as a selection cut for this landmark.

Catalogue chunk

core-25pcPart of the 371,766-source measured volume inside 100 pc.

Provenance

Provider

ESA Gaia Archive

Release

Gaia DR3

Licence

Gaia public archive data; follow ESA/Gaia/DPAC acknowledgement and citation guidance for publication.

Attribution

ESA/Gaia/DPAC and the Gaia Archive

Catalogue checked

2026-09-05

Catalogue SHA-256

0069111d383d2d2014a73819b637cefee233ed468309115c267098fe6092706d

Alias cross-identification

https://simbad.u-strasbg.fr/simbad/sim-id?Ident=Ross+128SIMBAD supplies only the visible common name for this source; the astrometry is Gaia.

Limitations COSMOS discloses

• Astronomic distance is a derived quantity from a truncated parallax, so it is not a direct measurement and it carries the stated parallax uncertainty.
• The rendered point size and colour come from bounded display transfers and must not be read as physical size, luminosity or temperature.
• Motion is propagated linearly from J2016.0. Over decades this approximation degrades, and COSMOS does not extrapolate it indefinitely.
• COSMOS names only a small set of nearby stars. It does not claim these are the nearest stars in existence, only that they are the measured landmarks the catalogue currently renders as destinations.