# Meteor Tally

> A naked-eye meteor shower planner and counter in the browser. Pick one of 13 major annual showers (Quadrantids,
> Lyrids, Eta Aquariids, Southern Delta Aquariids, Alpha Capricornids, Perseids, Draconids, Southern and Northern
> Taurids, Orionids, Leonids, Geminids, Ursids), the evening date and a site; the page computes sunset, the dark
> window, the Moon's phase and rise or set, and for each hour the radiant's altitude, the Moon's altitude, an
> estimated limiting magnitude and an estimated visible rate for one observer, picks the best window and a patch of
> sky to face, and draws it all on an overhead sky dome. A red night-vision tap counter logs shower and sporadic
> meteors in hourly periods with breaks. Each period gets a corrected ZHR with an exact Poisson 95% interval.
> Free, before you sign in. Two metered lanes run over the same night: PLAN (go / short-window / skip-tonight, a
> window, a facing, an expected count, a schedule, kit and backup nights) and REPORT (solid / usable / too-thin, the
> ZHR read honestly against the expected activity, period flags, caveats and a share text).

Derived from the SkillSafe agent skills @davila7/astropy (sky geometry, the plan lane) and
@davila7/statistical-analysis (counts, intervals, the report lane). Not affiliated with any astronomy organisation.

## How the numbers are made

- Sun and Moon: low-precision orbital formulas computed in the browser, good to a few arcminutes; topocentric
  parallax applied to the Moon. Sidereal time from the Julian date.
- Showers: approximate published radiants, ZHR, speeds, population indices, peak dates and activity windows, with a
  daily radiant drift and activity falling off by 10^(-b x days) from the peak. These are estimates, not a live
  calendar; outbursts are not predicted.
- Limiting magnitude: the sky class (city 4.0, suburb 5.0, rural 6.0, dark site 6.6) minus twilight and moonlight,
  a rule of thumb.
- Expected rate: HR = ZHR x sin(radiant altitude) / r^(6.5 - LM).
- ZHR from a count: ZHR = N x r^(6.5 - LM) / (Teff x sin h x (1 - cloud fraction)), per period; no ZHR when the
  radiant is under 10 degrees, half the field is clouded, or less than 5 minutes were watched. Interval: exact
  Garwood Poisson 95% bounds on N, scaled by the same factor. The overall ZHR pools qualifying periods.

## Contract (API)

Base URL https://api.skillsafe.ai/v1/app-api - send the run input bare to /estimate, /run or /run-stream.
Fields: task ("plan" or "report"), night_date, shower (JSON string), site (JSON string), notes; plan adds
hours_available and facts (JSON string); report adds periods, totals and brightness (JSON strings).
The reply is one JSON object; see https://meteor-tally.skillsafe.ai/api.html for every field and worked examples.

## Pages

- https://meteor-tally.skillsafe.ai/ - the app
- https://meteor-tally.skillsafe.ai/api.html - API tutorial in eight languages