Satellite Observations

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

Fetch the live list from the discovery endpoint below.

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"

An unknown slug returns 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" }
}

Each pass embeds a compact 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.

Getting Started

Use Cases

What are satellite observations?

Available missions

Discover missions

Localized descriptions

Filter passes by mission

Parameters

Response

Typical flow

​What are satellite observations?

​Available missions

​Discover missions

​Localized descriptions

​Filter passes by mission

​Parameters

​Response

​Typical flow

What are satellite observations?

Available missions

Discover missions

Localized descriptions

Filter passes by mission

Parameters

Response

Typical flow