MGCLS–H I

1.1 Home page

The welcome panel summarises the release: the fields with H I catalogues, the number of detections, the cluster redshifts, the noise, the column-density sensitivity and the beam. These numbers are computed from the released catalogues.
Sky View (press Show to open it) shows every field with its R₂₀₀ circle (dashed). Zoom in to see the H I galaxies and their contours (section 2); click a field or a galaxy to open its page.
The cluster table accepts cluster names, MGCLS field names, SBIDs and Capture IDs in its filter box; click a row to open the cluster.

1.2 Cluster pages

Fields are named as in the thesis; the X-ray-selected fields also show their Abell name in brackets, e.g. J2319.2−6750 (Abell 3990). Links and downloads use the database IDs.
The facts row gives the centre, redshift, luminosity distance D_L, angular scale and the number of H I detections.
The sky viewer, the plots and the completeness panel start closed, so that the page loads quickly on any device; press Show to open each of them. Locating a galaxy on the sky opens the sky viewer.
The sky viewer and the plots (projected phase space, H I mass against distance with the completeness limit, or any two catalogue columns) are linked: select galaxies in one and they are selected in the others and in the table. The ◎ button in a table row shows that galaxy on the sky.
Completeness shows the injection–recovery results for the field (section 3).

1.3 Galaxy pages

All measurements and the full SoFiA-2 catalogue row, the galaxy on the sky with its contours, its integrated H I spectrum with the W₅₀ and W₂₀ windows, and its place in its cluster (phase space; H I mass against W₅₀).

1.4 Search

Clusters: by cluster name, MGCLS name, SBID, Capture ID, position (RA and Dec in degrees or sexagesimal, with a radius) and velocity. Galaxies: by name, cluster, position and velocity. Several fields accept comma-separated values. Search URLs can be bookmarked.

The viewer is Aladin Lite (CDS). Choose the optical or infrared background above the map; scroll or use the buttons to zoom; drag to move. On cluster and galaxy pages the view stays within the 10 deg² around the field.
Markers: cluster members (|Δv| ≤ 3σ_v) in blue, other detections in orange, selected galaxies in magenta squares; the dashed red circle is R₂₀₀.
Contours, computed from the released cubelets, drawn as in the legend:
- 1σ (broken white) and 3σ (solid white): the moment-0 signal-to-noise map of each galaxy (SoFiA-2's own S/N map).
- 1 M_☉ pc⁻² (solid yellow; N_H I = 1.25×10²⁰ cm⁻², the H I size definition of Wang et al. 2016), shown once the view is narrower than 1.2°.
- Moment-0 levels (light blue, tick “moment-0 levels”): N_H I = 2ⁿN₀, with N₀ the galaxy's 3σ column density (the median N_H I of its pixels with 2.75 < S/N < 3.25), as in the SoFiA Image Pipeline; drawn for the selected galaxies and, below 0.8°, for every galaxy in view.
On the home page the galaxies appear below 12°, their contours below 3.5°. Hovering over a galaxy in the table, a plot or the sky highlights it in the others. On phones and tablets, pinch to zoom and tap to select.
N_H I = 1.104×10²¹(1+z)⁴ S/(a b) cm⁻², with S in mJy beam⁻¹ km s⁻¹ (radio-convention velocities) and a, b the beam axes in arcsec.

Completeness was measured with the Three-dimensional Emission Models for Blind-survey Assessments (TEMBA) injection–recovery pipeline: artificial galaxies modelled with 3D-Barolo were injected into each field's cube and recovered with SoFiA-2, as for the real detections.
The cluster page shows the recovered fraction against injected integrated flux (with the fitted logistic curve and S₅₀, S₉₀), against integrated S/N, and the flux recovery (catalogued over injected flux). Fractions carry 68 per cent binomial intervals; bars show the numbers injected and recovered.
The H I mass limit drawn on the mass–distance plot is M₉₀(D) = 2.356×10⁵ D² S₉₀.

On every cluster and galaxy page, press Download and choose the products. Then either Download ZIP archive (one archive, in a new tab), or Copy wget command or Copy curl command and paste it into a terminal.
The ZIP archive suits small selections. Large ones (cubes, many cubelets) are too big for the server to package: use a terminal command, which fetches each file directly from the archive.
The terminal shows a welcome banner, the progress of each file, a summary and a thank-you. The command needs bash and wget or curl; it resumes interrupted files, continues past missing ones and writes download_log.txt (plus missing_files.log or failed_files.log when needed). Set NO_COLOR=1 for plain output.

TOPCAT and Aladin Desktop: the “Send to TOPCAT / Aladin” buttons use SAMP. Start TOPCAT or Aladin first (they run the SAMP hub) and accept the connection request. Catalogues are also available as VOTable and CSV.
JSON API (for scripts and notebooks): /api/clusters, /api/cluster/<id>, /api/cluster/<id>/galaxies, /api/galaxy/<id>/<n>, /api/galaxy/<id>/<n>/spectrum, /api/cluster/<id>/completeness, /api/cluster/<id>/catalogue.vot, /api/catalogue.vot (all fields) and /api/corrections (every correction applied to the released catalogues).
Conventions: velocities are barycentric; v_rad is the radio convention, cz the optical one; flat ΛCDM with H₀ = 70 km s⁻¹ Mpc⁻¹ and Ω_m = 0.3; M_H I = 2.356×10⁵ D_L² S_int; Δv = (cz − cz_cl)/(1 + z_cl); members have |Δv| ≤ 3σ_v.
Citing: please acknowledge MGCLS–H I and cite the data, pipelines and services your work relies on; see Credits & licences.

The Home page and cluster-search results use the same displayed cluster columns and units. The table below matches what is shown on the website.

Displayed column	Units / format	Meaning
`Cluster Name (ID)`	–	Main cluster / field identifier used to open the cluster page.
`RA`	HH:MM:SS.ss	Right Ascension of the pointing centre.
`DEC`	±DD:MM:SS.ss	Declination of the pointing centre.
`z`	dimensionless	Cluster redshift.
`MGCLS Field Name`	`jHHMMSS±DDMMSS`	Short MGCLS field identifier derived from the pointing position.
`SBID`	`YYYYMMDD-NNNN`	MeerKAT schedule block identifier for the observation.
`Capture ID`	Unix timestamp	Archive / ingest capture identifier. These are numeric epoch-style values such as `1541694981`.
`HI Detections`	count	Number of H I detections in the staged cluster field.
`RMS`	mJy beam⁻¹	Per-channel noise at the pointing centre, σ₀: the robust rms of each channel within 10′ of the centre, median over channels, on the primary-beam-corrected cube (thesis Table 2.1). It rises towards the edge of the field. The N_H I sensitivity on the welcome panel is 3σ₀ over one 44 km s⁻¹ channel. Given for fields with H I catalogues.
`V (min)`, `V (max)`	km s⁻¹	Minimum and maximum radial-velocity coverage of the staged cube.
`BMIN`, `BMAJ`	arcsec	Synthesised beam minor and major axes.
`BPA`	deg	Beam position angle.

The cluster detail page and galaxy-search results use the following displayed galaxy columns. These are the website display units, which are intended for quick scientific browsing.

Displayed column	Units / format	Meaning
`Galaxy Name`	`MKTCS-HI JHHMMSS.ss±DDMMSS.s`	Primary MGCLS–H I source identifier for the detection.
`RA`	HH:MM:SS.ss	Right Ascension of the displayed H I source position.
`DEC`	±DD:MM:SS.ss	Declination of the displayed H I source position.
`V_rad`	km s⁻¹	Displayed radial velocity of the H I detection.
`S_int`	Jy km s⁻¹	Integrated H I line flux for the displayed source.
`W₂₀`, `W₅₀`	km s⁻¹	H I line widths measured at 20% and 50% of the peak level.

Cluster Name (ID): human-readable cluster / field name such as Abell-194.
MGCLS Field Name: compact position-based field name such as j012547-012223.
SBID: schedule block identifier in YYYYMMDD-NNNN format, for example 20181108-0033.
Capture ID: numeric archive capture identifier, for example 1541694981.

A useful rule of thumb is that SBIDs look like dated observing-block strings, while Capture IDs look like long integers.

Some internal or downloadable catalogues may include additional quantities that are not all shown in the website tables, for example DATE, NHI_min, NHI_max, FREQ_min, FREQ_max, NCHAN and mass-related columns. These remain scientifically useful, but the website prioritises the subset that is most helpful for interactive browsing and quick filtering.

Whenever a displayed website table and a downloadable catalogue differ in scope, use the units shown in the website table for on-screen interpretation, and the column headers inside the downloaded file for detailed offline analysis.