# Last Night's Sky

Every night, robotic survey telescopes photograph the sky and flag everything that
changed: exploding stars, black holes disrupting stars, moving asteroids. Last
Night's Sky is the public, plain-language front page for that stream — what changed
in the sky last night, where it is, and what it probably means.

Data: live alert classifications from the ALeRCE broker (ZTF survey; Rubin/LSST as
its public streams mature), sky imagery from CDS Strasbourg (Aladin/HiPS, hips2fits).
Classifications are machine-learning estimates and are always presented with their
probabilities — "probably" is part of the product.

Public JSON (no key, open CORS, `schemaVersion` field):
- /api/lastnight — last night's counts + curated highlights; add ?night=YYYY-MM-DD
  for any archive night back to 2018-06-01 (the same view the /?night= pages show)
- /api/events?class=&days=&limit= — recent curated events
- /api/event?id=ZTF... — full story payload for one object (classification,
  light curve, trend, links)
- /api/records — leaderboards (brightest/fastest/nearest/weirdest of the period)
- /api/stats — nightly counts series + norms (typical night, record night, rates)
  computed from the site's own archive
- /api/transients?category=&max_mag=&limit= (list) and ?id=ZTF… (detail with full
  per-filter photometry incl. upper limits, host galaxy, distance) — the transient
  observability layer's catalog; /tonight computes per-visitor verdicts client-side

Pages: / (sky map of last night), /event?id=... (story pages), /records, /science
(how it works), /about (credits & data use).

From the maker of cmetracker.ai.