Fast & lightweight HTTP gateway that serves solar position algorithm as a JSON REST API.
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Lightweight HTTP gateway that returns solar position data through a JSON REST API.
Send a POST /api/v1/sun request with a location and optional timestamp, get sunrise, sunset, solar noon, twilight times, sun angles, and the instantaneous sun position back as structured JSON.
Covers all solar events: sunrise, sunset, solar noon, day length, civil / nautical / astronomical twilights, azimuth and elevation at solar noon and at any requested instant. Handles polar night and polar day conditions. All times are returned in the observer's timezone (IANA, default UTC).
The binary embeds a web UI (dark/light mode, 15 languages) and an OpenAPI 3.1 spec — no external files, no runtime dependencies, no database. Solar calculations use the NREL Solar Position Algorithm (go-spa, Reda & Andreas, 2004), accurate to ±0.0003° in azimuth and zenith angle. Valid for years −2000 to 6000.
docker run -p 8080:8080 letstool/http2sun:latest
Open http://localhost:8080 to use the web UI, or query the API directly:
curl -s -X POST http://localhost:8080/api/v1/sun \
-H "Content-Type: application/json" \
-d '{"latitude": 48.8566, "longitude": 2.3522, "timezone": "Europe/Paris"}' | jq
| Field | Required | Default | Description |
|---|---|---|---|
latitude | ✅ | — | Decimal degrees, −90 to +90 |
longitude | ✅ | — | Decimal degrees, −180 to +180 |
timezone | ❌ | UTC | IANA timezone of the observer's location |
timestamp | ❌ | now | Unix timestamp in seconds (UTC epoch) |
elevation | ❌ | 0 | Observer altitude above sea level in metres |
pressure | ❌ | 1013.25 | Atmospheric pressure in hPa — affects refraction |
temperature | ❌ | 12.0 | Air temperature in °C — affects refraction |
delta_t | ❌ | auto | ΔT = TT − UT1 in seconds — auto-estimated via Espenak & Meeus (2006) if omitted |
{
"latitude": 48.86,
"longitude": 2.35,
"timezone": "Europe/Paris",
"timestamp": 1745107200,
"date": "2026-04-20",
"observer_elevation_m": 0,
"observer_pressure_hpa": 1013.25,
"observer_temperature_c": 12,
"delta_t_s": 75.27,
"sunrise": "06:49:42",
"sunset": "20:49:17",
"solar_noon": "13:49:30",
"day_length": "13:59:35",
"civil_twilight_begin": "06:15:47",
"civil_twilight_end": "21:23:12",
"nautical_twilight_begin": "05:33:49",
"nautical_twilight_end": "22:05:10",
"astronomical_twilight_begin": "04:46:58",
"astronomical_twilight_end": "22:52:02",
"sunrise_azimuth_deg": 72.17,
"sunset_azimuth_deg": 287.83,
"noon_elevation_deg": 52.76,
"noon_azimuth_deg": 180,
"polar_day": false,
"polar_night": false,
"current_azimuth_deg": 182.67,
"current_elevation_deg": 52.74,
"current_time_local": "13:56:57"
}
| CLI flag | Environment variable | Default |
|---|---|---|
--listen-addr | LISTEN_ADDR | 127.0.0.1:8080 |
CLI flag takes priority over the environment variable.
docker run -p 9090:9090 \
-e LISTEN_ADDR=0.0.0.0:9090 \
letstool/http2sun:latest
https://github.com/letstool/http2sun
This project is licensed under the Apache License, Version 2.0.
Copyright (c) 2026 letstool.net
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Content type
Image
Digest
sha256:80c6e1574…
Size
2.7 MB
Last updated
4 months ago
docker pull letstool/http2sun