What are satellite observations?
Satellite radar instruments — altimeters on most missions, a Ku-band scatterometer (SWIM) on CFOSAT — measure significant wave height along their orbital tracks, extending coverage to open ocean where no buoy reaches.
Each satellite overpass is grouped into a pass — one orbital segment over the network, with its own time window, geographic bounds, and a count of the observations it produced. Passes are attributed to the mission that produced them (e.g. CFOSAT), so you can filter to a single satellite.
Satellite observations surface through the buoy-namespaced endpoints below.
Available missions
Each pass is linked to one mission. The current set:
| Mission | Agency | Instrument |
|---|
| CFOSAT | CNES / CNSA | SWIM |
| Jason-3 | NASA / CNES / EUMETSAT / NOAA | Poseidon-3B |
| Sentinel-3A | ESA / Copernicus | SRAL |
| Sentinel-3B | ESA / Copernicus | SRAL |
| Sentinel-6A | ESA / EUMETSAT / NASA / NOAA | Poseidon-4 |
| SWOT nadir | NASA / CNES | Nadir altimeter |
| Saral/AltiKa | ISRO / CNES | AltiKa |
| CryoSat-2 | ESA | SIRAL |
| HaiYang-2B | CNSA / NSOAS | Radar altimeter |
| HaiYang-2C | CNSA / NSOAS | Radar altimeter |
Discover missions
GET /buoys/satellites lists every mission with its metadata and a count of recorded passes. Use a returned slug as the filter value for satellite passes.
curl -H "Authorization: Bearer YOUR_API_KEY" \
"https://api.thebuoy.app/v2/buoys/satellites"
{
"status": "success",
"data": {
"satellites": [
{
"slug": "cfosat",
"name": "CFOSAT",
"agency": "CNES / CNSA",
"instrument": "SWIM",
"description": "Joint French–Chinese mission measuring ocean surface wind and directional wave spectra with the SWIM scatterometer.",
"image_url": null,
"pass_count": 220
}
],
"count": 12
},
"meta": { "timestamp": "2026-05-27T09:00:00Z" }
}
Localized descriptions
Mission description is available in English and French. Select the language with ?locale= (or the Accept-Language header); it defaults to English.
curl -H "Authorization: Bearer YOUR_API_KEY" \
"https://api.thebuoy.app/v2/buoys/satellites?locale=fr"
{
"slug": "cfosat",
"name": "CFOSAT",
"description": "Mission franco-chinoise mesurant le vent de surface et les spectres directionnels des vagues à l'aide du diffusiomètre SWIM."
}
Filter passes by mission
GET /buoys/satellite_passes returns recent passes. Pass mission (a slug from the discovery endpoint) to get only that satellite’s passes.
# Only CFOSAT passes
curl -H "Authorization: Bearer YOUR_API_KEY" \
"https://api.thebuoy.app/v2/buoys/satellite_passes?mission=cfosat"
404 resource_not_found. Omit mission to get passes from all satellites.
Parameters
| Parameter | Type | Default | Description |
|---|
mission | string | — | Filter to one mission, by slug (see /buoys/satellites) |
active_only | boolean | true | Only passes that have fresh, displayable buoy readings |
since | string (ISO 8601) | — | Only passes at or after this timestamp |
limit | integer | 20 | Max passes to return (max 100) |
Response
{
"status": "success",
"data": {
"satellite_passes": [
{
"id": 1842,
"name": "Bay of Biscay pass · CFOSAT · 14 May 10:00 UTC",
"external_id": "cfosat-...",
"satellite_pass_id": "cfosat-...",
"platform": "CFOSAT",
"mission": { "slug": "cfosat", "name": "CFOSAT" },
"started_at": "2026-05-14T10:00:00Z",
"ended_at": "2026-05-14T10:20:00Z",
"buoy_count": 6,
"observation_count": 18,
"bounds": { "south": 43.0, "west": -5.0, "north": 47.0, "east": -1.0 }
}
],
"count": 1
},
"meta": { "timestamp": "2026-05-27T09:00:00Z" }
}
mission reference (slug + name); platform is the raw label stored on the pass. Use bounds to place the pass on a map and buoy_count / observation_count to gauge its density.
Typical flow
Discover missions
Call GET /buoys/satellites once to learn the available slugs and pass counts.
Filter passes
Call GET /buoys/satellite_passes?mission=<slug> to pull that satellite’s recent passes.
Map or chart
Use each pass’s bounds, time window, and counts to render coverage or feed a dashboard.
