Sunrise, sunset and golden hour times

Work out sunrise, sunset, solar noon, day length, twilight, golden hour and blue hour for any point on Earth and any date. Give a latitude and a longitude, and the actor returns a clean table of solar times with the local timezone already applied.

Everything is computed offline. There is no web API behind it, no key to get, no sign up, and no rate limit to trip over. The times come from the standard NOAA solar position algorithm through the astral library, and the timezone for each place is read from an offline boundary map. Nothing calls out to the internet at run time, so the actor has no moving parts to break and needs no upkeep.

What it does

For each location and each date it returns:

• Sunrise and sunset.
• Solar noon, the moment the sun sits highest.
• Day length, as a clock value and as decimal hours.
• Civil, nautical and astronomical twilight, both the dawn and the dusk side.
• Morning and evening golden hour, the warm low-sun window photographers plan around.
• Morning and evening blue hour, the cooler window just outside golden hour.

The timezone is detected from the coordinates, so the times you get back are already local to the place you asked about. You can override it by naming an IANA zone such as Europe/Paris.

Who it is for

Photographers and film crews scheduling around the light, solar and outdoor planners, event and travel planning, and anyone building a calendar or app that needs daylight windows for a list of places.

Input

Set these in the input form or pass them as JSON.

• Locations. One object per place, each with a name, a latitude, a longitude, and an optional timezone. Leave the timezone out and it is worked out from the coordinates.
• Start date. The first day to calculate, as YYYY-MM-DD. Leave it empty to use today.
• Number of days. How many days from the start date to cover. You get one row per location per day.
• Time format. 24 hour like 05:56, 12 hour like 5:56 AM, or a full ISO datetime with the local offset.
• Include golden hour and blue hour. On by default.
• Include nautical and astronomical twilight. On by default. Civil twilight is always included.

Example input:

{
  "locations": [
    {"name": "San Francisco", "latitude": 37.7749, "longitude": -122.4194},
    {"name": "Reykjavik", "latitude": 64.1466, "longitude": -21.9426, "timezone": "Atlantic/Reykjavik"}
  ],
  "startDate": "2026-06-21",
  "days": 1,
  "timeFormat": "24h"
}

Output

One dataset row per location per date. Each row carries the location name, coordinates, timezone and date, then the solar times: sunrise, solar noon, sunset, day length and decimal day length, civil dawn and dusk, nautical and astronomical dawn and dusk, and the golden and blue hour windows.

Example row:

{
  "name": "San Francisco",
  "date": "2026-06-21",
  "latitude": 37.7749,
  "longitude": -122.4194,
  "timezone": "America/Los_Angeles",
  "sunrise": "05:47",
  "solar_noon": "13:12",
  "sunset": "20:35",
  "day_length": "14:48:07",
  "day_length_hours": 14.802,
  "civil_dawn": "05:16",
  "civil_dusk": "21:07",
  "golden_hour_evening_start": "19:56",
  "golden_hour_evening_end": "20:55",
  "blue_hour_evening_start": "20:55",
  "blue_hour_evening_end": "21:07",
  "nautical_dawn": "04:37",
  "astronomical_dawn": "03:54",
  "note": ""
}

Polar days and nights

Above the Arctic and below the Antarctic circles there are dates when the sun never sets or never rises. On those days the affected times come back empty and the note explains which case it is, so a run over a long list of places still finishes cleanly.

How the times are worked out

Solar positions use the NOAA algorithm as implemented in astral. Golden hour is the span while the sun sits between 4 degrees below and 6 degrees above the horizon. Blue hour runs from 6 to 4 degrees below. Civil, nautical and astronomical twilight use the usual 6, 12 and 18 degree sun depressions. Timezones come from the timezonefinder boundary data. All of it runs from local computation, which is why the actor stays at zero maintenance.