Every Gaia DR3 source within 1° of the Pleiades cluster centre (56.75°, 24.12°): positions, parallaxes, proper motions and three-band photometry, as released by ESA.
This page follows the data from the Gaia mission to the standardised 15,502 × 3 matrix of proper motions and parallaxes. The earliest level held is the released catalogue, so the steps before it are documented by ESA and the Gaia consortium, and the steps after it are reproduced here.
Gaia Collaboration; data processed by DPAC and published by the European Space Agency.
Gaia DR3, Version 1.1 (upstream release).
ESA’s Gaia spacecraft measures the positions, parallaxes and proper motions of stars by scanning the sky repeatedly, and their brightness in a broad G band and in blue (BP) and red (RP) bands. The Gaia Data Processing and Analysis Consortium (DPAC) combines all observations of each source into one solution; Gaia DR3 publishes them.
From the sky to the held file
- DocumentedGaia spacecraft
Repeated scans of the whole sky, 25 July 2014 – 28 May 2017
- DocumentedData processing (DPAC)
Astrometric and photometric solution for each source from all its transits
- DocumentedGaia DR3 release
gaiadr3.gaia_sourcein the ESA Gaia archive - ReproducedArchive query
All sources within 1° of (56.75°, 24.12°); checked against the archive
- HeldHeld file
27,545 rows × 22 columns, CSV
Documented: described by ESA and DPAC, not rerun here. Reproduced: rerun or checked here. Held: the bytes this page reads.
One acquisition unit: one source
A row is one source: its solution from every transit across the observing period. Sources with too few good observations receive a position only, with no parallax or proper motion.
What each row records
| Column | Unit | Meaning |
|---|---|---|
source_id | — | Gaia source identifier |
ra, dec | deg | Position at the reference epoch 2016.0 |
ra_error, dec_error | mas | Standard uncertainty of the position |
parallax, parallax_error | mas | Parallax and its uncertainty; distance ≈ 1000 / parallax pc |
parallax_over_error | — | Parallax divided by its uncertainty |
pm | mas yr⁻¹ | Total proper motion |
pmra, pmdec (+ _error) | mas yr⁻¹ | Proper motion in right ascension (× cos dec) and declination |
phot_g_mean_flux (+ _error) | e⁻ s⁻¹ | Mean G-band flux and its uncertainty |
phot_g_mean_mag | mag | G magnitude |
phot_bp_…, phot_rp_… | e⁻ s⁻¹, mag | The same three fields for the BP and RP bands |
The file, opened
Its first rows, all columns:
The catalogue as a signal
Proper motion of the 23,717 sources that have one. Most field stars scatter around zero. The Pleiades stars share one motion across the sky and form the tight clump, which is visible before any processing.
What the file covers
Sky positions of all 27,545 sources; brighter sources are drawn larger. The circle is the 1° cone.
What the raw record does not give you directly
- 3,828 sources have no parallax or proper motion. They have a position-only solution; the brightest source in the field is one of them.
- 3,605 parallaxes are zero or negative. For distant stars the measurement noise exceeds the parallax; these are measurements, not errors.
- There is no magnitude uncertainty column. It has to be derived from the flux and its uncertainty.
- Nothing says which stars belong to the cluster. The cone mixes Pleiades members with foreground and background stars.
- The release is not named in the file. Its photometry matches Gaia DR3, not the earlier EDR3 (see the checks below).
The table lists every step from the released catalogue to the matrix: the provider’s processing, the archive query that produced the file (rerun here as step 2), and the submitted notebook’s cleaning, replayed on the held file.
| Step | Evidence | Operation | Result |
|---|---|---|---|
| 1 | Documented | DPAC solves each source’s astrometry and photometry; ESA releases Gaia DR3 | the gaia_source table |
| 2 | Reproduced | Query all sources within 1° of (56.75°, 24.12°) | 27,545 sources |
| 3 | Reproduced | Drop rows with any missing value | 23,543 rows |
| 4 | Reproduced | Derive the G-magnitude uncertainty, 2.5 / ln 10 × flux error / flux, and the BP − RP colour | two new columns |
| 5 | Reproduced | Keep positive parallax | 19,966 rows |
| 6 | Reproduced | Keep G-magnitude uncertainty below 0.005 mag | 15,502 rows |
| 7 | Reproduced | Take pmRA, pmDec and parallax as features; keep position, colour and G magnitude aside for checking the clusters afterwards | 15,502 × 3 |
| 8 | Reproduced | Standardise each feature with its mean and standard deviation over the 15,502 rows | design matrix |
Where the sources go
Why each dropped source goes
| Reason | Sources |
|---|---|
| G error ≥ 0.005 mag | 4,464 |
| no astrometry | 3,828 |
| parallax ≤ 0 | 3,577 |
| missing photometry | 174 |
Follow one source
Pick a source to see it at each step, from its catalogue row to the row the matrix stores.
Checks against the archive
| Check | Result |
|---|---|
| Sources in the 1° cone at (56.75°, 24.12°) | 27,545 in the archive, 27,545 held |
| Parallaxes: count and sum | 23,717; sum identical |
| Proper motion in RA: sum | identical |
| Source identifiers: range and checksum | identical |
| G flux: sum against Gaia DR3 | identical |
| G flux: sum against Gaia EDR3 | differs (6,015,637,132.2 vs 6,015,661,020.2) |
| Notebook row counts | 23,543 and 15,502, as recorded |
The file is the full content of the cone. Its astrometry is the same in both releases; its photometry is Gaia DR3’s.
Each row is one kept source; the three columns are its proper motion in right ascension and declination and its parallax, each standardised to mean 0 and standard deviation 1. Hover a bar to read it.
The long tails are real: nearby stars have large parallaxes and proper motions. The cluster appears as a small second peak in each feature: near +1.6 in pmRA, −2.6 in pmDec and +3.9 in parallax.
First rows
| Feature | Unit | Meaning |
|---|---|---|
pmra | z | Proper motion in RA, standardised: (value − 3.687) / 10.416 mas yr⁻¹ |
pmdec | z | Proper motion in Dec, standardised: (value − (-6.293)) / 14.866 mas yr⁻¹ |
parallax | z | Parallax, standardised: (value − 1.131) / 1.629 mas |
Columns kept aside for checking
| Column | Unit | Meaning |
|---|---|---|
ra, dec | deg | Sky position; for checking a clustering afterwards, never an input |
bp_rp | mag | BP − RP colour |
phot_g_mean_mag | mag | G magnitude |
ESA's Gaia DR3 DOI record: data hosted in the ESA Space Science Archives are distributed under the CC BY-NC 3.0 IGO licence. This work has made use of data from the European Space Agency (ESA) mission Gaia, processed by the Gaia Data Processing and Analysis Consortium (DPAC). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.
- The dataset was recorded as Gaia EDR3. Its photometry matches Gaia DR3, and the astrometry used in the matrix is identical in both releases.
- No membership labels accompany the cone, so a clustering cannot be scored against a verified list of members here.
- The screens remove 3,577 sources with parallax ≤ 0 and 4,464 faint sources. The kept sample therefore favours nearer and brighter stars.
- The archive checks compare counts and sums, not every row.
European Space Agency, Gaia Collaboration, 2022, Gaia DR3, Version 1.1, European Space Agency, DOI 10.5270/esa-qa4lep3.
Pleiades membership explorer: Gaussian-mixture, DBSCAN and HDBSCAN membership of the cluster; and its Insight page.