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Event sources · evidence and sources

Sky events and alerts

Where the calendar entries and the living-sky alerts come from, and how often each feed is read.

Also known as calendar, alerts, sky-events.ics.

astronomy-engine · 33 min Position basis, the same label the app shows on the selection card.

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Every aspect, with its origin

One record per aspect. The origin says what kind of thing each value is; the source says where it came from; the limit says what it cannot tell you.

ObservedCatalogComputedReconstructedIllustrativeUndocumented
Position Computed

Eclipses, seasons, oppositions and elongations

The sky-events calendar (.ics) and the in-app event list are computed with astronomy-engine for a rolling 24-month window: global solar and lunar eclipse circumstances, equinoxes and solstices, planetary oppositions and greatest elongations.

Sourceastronomy-engine
EpochGeneration date plus 24 months
Retrieved
Methodscripts/generate-sky-events.mjs (SearchGlobalSolarEclipse, SearchLunarEclipse, Seasons, relative-longitude search for oppositions).
LimitGlobal circumstances only. Local eclipse contact times come from the per-city eclipse pages, which repeat the calculation for one observer.
Position Catalog

Meteor shower maxima

Shower activity windows, radiants, ZHR and the solar longitude of maximum follow the IMO working list. The peak instant for a given year is found by searching for the Sun reaching that longitude, so it moves with the calendar rather than sitting on a fixed date.

SourceInternational Meteor Organization shower calendar
MethodOne shared table (src/shared/meteorShowers.js) feeds the app, the emails and the .ics file.
LimitObserved rates vary from year to year; the ZHR is the nominal maximum.
Orbit Catalog

Live alerts: asteroid close approaches

Close approaches inside the Moon's distance come from the JPL CNEOS close-approach API, with nominal and minimum distances and relative speed.

SourceJPL CNEOS close-approach data (cad.api)
LimitNewly discovered objects can have large orbit uncertainty; the minimum distance is the 3-sigma bound.
Identity Observed

Live alerts: bright novae and supernovae

The sky-alerts cron reads the "Bright Supernovae, Active Objects" list and keeps only transients brighter than magnitude 12 that were discovered within 30 days and observed within 14 days.

SourceRochester Astronomy bright supernovae list
LimitAmateur-compiled registry; magnitudes are the latest reported estimates.
Identity Observed

Live alerts: comet brightness

Observed comet magnitudes come from the COBS observation database (median of the most recent estimates over 45 days) and are compared with the catalog's predicted brightness law.

SourceCOBS Comet Observation Database
LimitVisual estimates by many observers; scatter of half a magnitude is normal.
Identity Observed

Live alerts: geomagnetic storms

Geomagnetic watches, warnings and alerts are read from NOAA SWPC and stored with their issue time and G-scale level.

SourceNOAA Space Weather Prediction Center alerts
LimitA watch is a forecast, not an observation; the Kp value is the storm measure.

Engine and frame

  • Engine: astronomy-engine (analytic planetary and lunar model; Sun through Pluto and the Moon)
  • Eclipse circumstances: astronomy-engine global eclipse search (Besselian elements), peak times in UTC
  • Meteor peaks: instant the apparent solar longitude reaches the IMO value for the shower

What is not measured

Nothing on this page is a reconstruction or a schematic; every record above is observed, catalogued or computed.

Dataset freshness

Snapshots this page depends on, read from the generated manifests at request time.
DatasetBundle updatedHorizonAutomated
Current comets and near-Earth asteroids
JPL Small-Body Database
Source retrieved:
Osculating elements at the snapshot epoch; propagated as two-body conics Yes, daily (Trigger.dev)
Trigger.dev → private Blob snapshots
Last successful check: 23 October 2026 · success
Searchable comet catalog (all comets)
JPL Small-Body Database
Source retrieved:
Every JPL comet record with elements and photometric parameters Yes, daily (Trigger.dev)
Trigger.dev → private Blob snapshots
Last successful check: 23 October 2026 · success
Sky events calendar (.ics)
astronomy-engine plus the IMO meteor shower list
 Next 24 months from the generation date Yes, weekly (Monday data job)
npm run generate:calendar

Sources cited

More

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