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About & methodology

Sources

Source Agency What Since
Sentry API NASA JPL Full risk list and removed objects live archive
NEOCC risk list ESA Full risk list and special list live archive
SBDB API NASA JPL Orbit solution, designations, size live, incremental
Internet Archive captures of the Sentry API NASA Full list, irregular dates 2018
Internet Archive captures of the NEOCC risk page ESA Top rows only, weekly sample 2016
No Results

How history is built

  1. Bronze: every raw response is stored unchanged, content-addressed by hash.
  2. Silver: each response is parsed into typed rows, validated by data contracts.
  3. Gold (dbt + DuckDB): one observation per list per day; consecutive observations are collapsed into versions (slowly changing dimension, type 2) per object and list.

A new version starts when an object enters a list, re-enters after a complete snapshot showed it absent, or its solution changes: impact probability (to 3 significant digits), Torino scale, number of virtual impactors, impact year range or last observation date. The Palermo Scale alone is excluded because it drifts as the potential impact date approaches.

Uncertainty windows

Snapshots are discrete, so every event has a window: it happened after the last snapshot that didn't show it and by the first one that did. Daily live snapshots make that window one day; archive captures can make it months. Partial (top-N) snapshots can show objects but never prove their absence, so they never end a version.

Comparing the agencies

Objects are matched by their primary designation (via SBDB, so renamed or numbered objects merge). For objects on both lists, the cumulative impact probabilities are compared: agrees within 3×, differs 3–10×, diverged beyond 10×.

Caveats

  • This is an independent archive, not an official product of NASA or ESA. Always check CNEOS and NEOCC for authoritative values.
  • Nearly all listed objects are small and very unlikely to hit Earth.

Code: private repository two-skies. Alerts: RSS.