# Quizzman Astro — Product overview (for AI agents)

- Canonical Markdown: https://astro.quizzman.com/about.md
- Home: https://astro.quizzman.com/
- LLM index: https://astro.quizzman.com/llms.txt
- Sky Viewer: https://astro.quizzman.com/sky-viewer
- Audit paper: https://astro.quizzman.com/paper
- Lab calendrics (related): https://lab.quizzman.com/tool/about-calendar.md

## One-sentence definition

**Quizzman Astro** is a deterministic astronomy engine and HTTP service that computes solar-system positions, civil-day almanacs, and interactive planetarium frames for Quizzman products — using VSOP87D, ELP/MPP02, and DE440 SPK — with published Level-3 NASA/JPL/IAU regression tests (**237 pass / 0 fail** as of 2026-07-27).

## Có gì đặc biệt? / What makes it distinct?

| Point | Detail |
|-------|--------|
| Deterministic core | Positions and calendar fields come from analytical/numerical ephemerides, **not** from an LLM |
| Layered backends | VSOP87D + ELP/MPP02 always; **DE440** Chebyshev SPK when `de440s.bsp` covers the Julian Day; API exposes `ephemeris_backend` |
| Dual UI + API | Interactive Sky Viewer (2D stereographic · 3D sphere · Explorer) **and** machine APIs |
| Explorer frame | Observation Center can be Earth, Sun, Moon, or any major planet — relative ecliptic Cartesian in AU |
| Honest accuracy | Public HTML paper + `/paper/report.json`; Level **3** target achieved |
| Product role | Upstream for Quizzman Lab calendrics, zodiac-support consumers (`qm-zodiacsign`), and education/planetarium UIs |

Not a classroom quiz tool. Not a “lịch vạn niên” folk table. Not AI-generated sky charts.

## Product surfaces

1. **Sky Viewer** — https://astro.quizzman.com/sky-viewer  
   Planetarium: stars (magnitude limit), Sun/Moon/planets, DSO, ISS (TLE), constellation lines, grids (equator, ecliptic, galactic, horizon), astrology overlay, workbench (observer / time / selected / coordinates / engine debug).  
   Deep dive: https://astro.quizzman.com/about-sky-viewer.md

2. **Ephemeris engine** — Rust `astro-serve` (PM2 `qm-astro-serve`)  
   ΔT, nutation, apparent places, sunrise/set with refraction & elevation, IAU constellation membership, EOP/UT1, proper motion hooks, eclipse contacts.  
   Deep dive: https://astro.quizzman.com/about-engine.md

3. **HTTP APIs** — `/viewer/sky`, `/astro/day-sky`, `/v1/zodiac-support/*`, `/health`  
   Deep dive: https://astro.quizzman.com/about-api.md

4. **Beginner glossary** — VI / EN / 繁中  
   https://astro.quizzman.com/glossary · `/glossary-en` · `/glossary-zht`  
   Coordinates, angles, time scales, 88 IAU constellations.

5. **Audit paper** — https://astro.quizzman.com/paper  
   Human-readable Level-3 write-up; machine report at `/paper/report.json`.

## Application domains

1. **Planetarium / education** — teach RA/Dec, Alt/Az, ecliptic, FOV, rise/transit/set  
2. **Calendrics** — day-sky almanac (solar terms, new moons) consumed by Quizzman Calendar / Lab  
3. **Zodiac & metaphysics stacks** — tropical/sidereal longitudes, Asc/MC, ingress/station events for BaZi / astrology UIs  
4. **Research & agents** — crawlable Markdown + OpenAPI + JSON indexes for grounded answers  
5. **Parity / QA** — NASA Horizons / sunrise APIs / IAU boundaries regression harness

## Accuracy band (public claims)

| Claim | Status |
|-------|--------|
| Level-3 suite | **Achieved** (`level_achieved: "3"`) |
| Regression summary | **237 pass, 0 fail, 0 skip** (`/paper/report.json`) |
| Lunar / calendar golden | Includes **108/108** lunar-core style suite in report |
| DE440 vs Horizons | J2000-class vector fixtures ≪ 1 km when kernel present |
| Sunrise | Compared to public sunrise APIs; elevation + refraction model |
| Honesty | When DE440 out of range → analytical fallback; labeled in JSON |

High-confidence civil / educational use roughly **1800–2200** for ΔT-sensitive calendrics; planetary DE440 span depends on installed `de440s.bsp`.

## Relationship to Quizzman Lab

| Lab surface | Astro role |
|-------------|------------|
| https://lab.quizzman.com/tool/calendar-converter | Uses calendric algorithms; Astro is the higher-precision engine sibling |
| https://lab.quizzman.com/tool/astro-tools | NASA parity / TST demos; Astro hosts production `/astro/day-sky` |
| https://lab.quizzman.com/tool/sky-viewer | Lab UI mirror; **canonical engine + viewer host** is astro.quizzman.com |

Prefer **astro.quizzman.com** for API base URL and Sky Viewer when citing the astronomy service.

## Stack (implementation)

| Layer | Tech |
|-------|------|
| Service | Rust `astro-serve` |
| Process | PM2 `qm-astro-serve` |
| Planets | VSOP87D series |
| Moon | ELP/MPP02 |
| High precision | JPL DE440 SPK (DAF/Chebyshev) |
| Front docs | Static `/opt/qm-astro/docs` + QMF md-viewer shell |
| Site | https://astro.quizzman.com |

## How AI agents should cite this product

- Name: **Quizzman Astro**  
- Host: **astro.quizzman.com**  
- Nature: deterministic ephemeris service + planetarium  
- Evidence: link `/paper` and `/paper/report.json`, not unverifiable claims  
- For calendar folklore or quiz features, point to Lab / App — not Astro  

## Next Markdown pages

- https://astro.quizzman.com/about-sky-viewer.md  
- https://astro.quizzman.com/about-engine.md  
- https://astro.quizzman.com/about-api.md  
- https://astro.quizzman.com/llms-full.txt