Methodology and limitations

Acquisition source

Planned opportunities come from ESA’s Sentinel-2 acquisition-plan KML files. Only placemarks whoseMode=NOBSare eligible. The published swath connects simplified strip corners, so the interface labels it “planned footprint” rather than an exact delivered-product boundary.

Weather score

MET Norway’s cloud_area_fraction is modelled cloud coverage for a forecast grid cell. The displayed clear-fraction proxy is simply1 − median cloud fraction across up to nine AOI samples. It is not the probability that an acquisition will be usable. Missing or out-of-range values remain unscored.

Forecasts are conditionally cached using provider expiry and modification headers. A stale result is labelled and served for at most six hours; acquisition results remain available if weather fails.

Degraded orbit fallback

CelesTrak OMM elements drive the displayed orbit and, only when no valid plan snapshot exists, an explicitly marked predicted-only fallback. Its modeled swath uses a nominal 145 km half-width around the propagated ground track. It is useful for visualizing a possible crossing, but it is not an ESA footprint and does not assert that Sentinel-2 will image the target.

Predicted results open in 2D. A user may deliberately open the same modeled geometry in 3D. The fallback refines each bracketed ground-track minimum to sub-second precision before applying the swath threshold.

Probability gate

The product will not display a probability_usableuntil each lead-time bucket contains at least 1,000 matched observations, held-out Brier score beats climatology and the raw proxy, and expected calibration error is at most 0.05 overall. The defined event will be “at least 80% of the AOI is usable.”

Product availability

A feature-gated reconciliation job can compare completed plans with Sentinel-2 L2A products in the Copernicus Data Space STAC catalog. A stable match can mark a plan as available; a complete search without a match remains acquired pending. Provider errors write no status, and product absence alone is never labelled as a cancellation. Reconciliation starts disabled until staged validation and provider-load checks are complete.

Privacy

The anonymous planner does not persist user AOIs. Cookieless funnel events contain only aggregate result buckets and degraded-state labels. ClearSKY links never include coordinates or AOI geometry. Shared AOIs live in the URL fragment, which browsers do not send to the server.

The operational maps use CARTO and OpenStreetMap tiles. Their tile servers receive standard tile coordinates for the visible viewport, which can approximate the area being viewed, but they do not receive the submitted GeoJSON/KML AOI or planner results.