# Star Catalog

Look up bright and nearby stars, cone searches, constellations, distances, luminosity and visibility by latitude.

## How to pay

Machine-payable over x402. USDC on: Base (eip155:8453), Solana (solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp), Polygon (eip155:137), Arbitrum One (eip155:42161).
No accounts. No API keys. No signup. The paying wallet is the account.

## Machine-readable

- OpenAPI: https://star-catalog.x402tookit.com/openapi.json
- x402 manifest: https://star-catalog.x402tookit.com/.well-known/x402
- Catalog (free): https://star-catalog.x402tookit.com/catalog
- Health (free): https://star-catalog.x402tookit.com/health
- Uptime (free): https://star-catalog.x402tookit.com/uptime

## Endpoints (8)

### GET /brightest-stars — $0.02
The N brightest stars by apparent magnitude in the whole sky or in one constellation (name or IAU code).
Params: n?: integer, constellation?: string
Example: https://star-catalog.x402tookit.com/brightest-stars?n=5

### GET /constellation-info — $0.02
IAU constellation facts: 3-letter code, genitive, bright stars; pass 'list' for all 88 constellations.
Params: q: string
Example: https://star-catalog.x402tookit.com/constellation-info?q=Canis+Major

### GET /nearest-stars — $0.02
The N closest stars to the Sun (max 200) with distance in light years, parallax, magnitude and spectral type.
Params: n?: integer
Example: https://star-catalog.x402tookit.com/nearest-stars?n=8

### GET /star-distance-and-luminosity — $0.02
From apparent magnitude and parallax (mas): distance, absolute magnitude M = m + 5 + 5 log10(p arcsec), solar luminosity.
Params: apparentMagnitude: number, parallaxMas: number
Example: https://star-catalog.x402tookit.com/star-distance-and-luminosity?apparentMagnitude=-1.44&parallaxMas=379.21

### GET /star-lookup — $0.02
Look up a star by name, Bayer (Alpha CMa), HR, HIP, HD or Gliese number: magnitude, spectrum, J2000 position, distance.
Params: q: string
Example: https://star-catalog.x402tookit.com/star-lookup?q=Sirius

### GET /star-visibility-from-latitude — $0.02
Whether a star (or declination) ever rises above the horizon from a latitude, circumpolar status, and max altitude.
Params: latitudeDeg: number, star?: string, declinationDeg?: number
Example: https://star-catalog.x402tookit.com/star-visibility-from-latitude?latitudeDeg=40&star=Sirius

### GET /stars-in-constellation — $0.02
List catalogued stars in an IAU constellation (name or 3-letter code), brightest first, with an optional named-only filter.
Params: constellation: string, namedOnly?: boolean, limit?: integer
Example: https://star-catalog.x402tookit.com/stars-in-constellation?constellation=Orion&namedOnly=true&limit=10

### GET /stars-near-sky-point — $0.02
Cone search: stars within a radius (max 30 deg) of an RA/Dec J2000 point, nearest first, with separations.
Params: raDeg: number, decDeg: number, radiusDeg?: number, limit?: integer, maxMagnitude?: number
Example: https://star-catalog.x402tookit.com/stars-near-sky-point?raDeg=84.0533&decDeg=-1.2019&radiusDeg=2&limit=10&maxMagnitude=3

## Terms

Star data is the bright (V <= 6.5) and nearest-200 subset of the HYG database v4.1 (Hipparcos, Yale Bright Star and Gliese catalogues), CC BY-SA 4.0, provided as is. Positions are J2000 without proper-motion propagation; distances come from catalogue parallaxes with uncertainty; visibility ignores refraction, twilight, weather and local horizon. Not for navigation, pointing or professional astrometry.