Why a fixed alarm misses the light
Risetime is a clock app for Android: alarms at a fixed time or following the sun, and timers that repeat and chain. No ads ever and completely offline.
You know when the light is good. The problem is that it moves: sunset in New York runs from 16:31 on 21 December to 20:30 on 21 June. A fixed alarm for golden hour is wrong within two weeks and useless within a month.
Risetime sets an alarm on the sun's angle rather than on a clock time, and the angle is what actually defines those windows.
Which sun angle is golden hour, or blue hour?
| What you're after | The sun is… | In Risetime |
|---|---|---|
| Golden hour, evening | at about 6° above the horizon | a solar angle anchor, +6° evening |
| Blue hour, evening | at about 4° below the horizon | a solar angle anchor, −4° evening |
| Golden hour, morning | climbing past about 4° below the horizon, until 6° above | −4° morning |
| Astronomical night | 18° below | −18° evening, and −18° morning for when it ends |
Definitions vary between photographers; these are the common ones. In the evening, golden hour begins as the sun sinks past 6° above the horizon. In the morning it runs the other way: it begins as the sun climbs past about 4° below, just after blue hour, and ends at 6° above. So a morning alarm goes on −4°, not +6°. The angle is adjustable. For blue hour, set a solar angle anchor to −4°, the usual definition: the alarm rings when the sun passes 4° below the horizon. Whatever angle you work with, the app holds it at every latitude and season, which a "30 minutes before sunset" rule of thumb cannot do, because the length of twilight changes with both. In London on 21 June, +6° falls at 20:27 and sunset at 21:21: nearly an hour apart. In New York the same evening, 19:49 and 20:30: forty minutes.
How do I set a golden hour alarm?
- Open Settings → Anchors and press +.
- Keep the type on A solar angle, and set your angle: tap the value to type it, and choose morning or evening.
- Name it (Golden hour, Blue hour, Night sky), pick a colour, and save.
- On the Alarms tab, set an alarm on it: at the anchor, or thirty minutes before to reach the spot.
A working week, and the light at the weekend
Most of us are not shooting for a living:
| Moment | Alarm | Days |
|---|---|---|
| Wake-up | 06:45 | Mon–Fri |
| School run | 08:10 | Mon–Fri |
| Pack the bag | 30 min before Golden hour | Sat & Sun |
| Blue hour | Blue hour | Sat & Sun |
| Stars | Night sky | Fri & Sat |
Clock alarms for the week, sun alarms for the light: the same list, the same app.
On the road, and off the grid
- Travelling? Turn on Auto-update location in Settings and your alarms follow you: a trip, a new city, a coastline.
- No signal at the spot? Risetime computes the sun's position on the phone, with an astronomical library. It has no internet permission at all, so it cannot depend on a connection: airplane mode, a canyon, a boat. The alarm still knows when the light comes.
- No tracking, no account, no ads. Your location never leaves the phone. Privacy policy
Can I set an alarm for astronomical night?
Astronomical night is the window between the evening and the morning moments when the sun is 18° below the horizon. Set an anchor at each and you hold both ends of the dark.
Far north or far south, that window closes for part of the year: in London the sun does not reach −18° from 23 May to 21 July. Risetime says so when you create the anchor, with the dates for your own location, and on those nights the alarm stays silent rather than ring at a time the sky never produces.
What it costs
Risetime is free for up to three alarms and three timers – for good. Need more? Use those three first, and see if it's worth your support: supporters get unlimited alarms and timers, yearly or once. If not, I'll be happy to hear you out.
Frequently asked questions
- Why doesn't a fixed-time alarm work for golden hour?
- The light moves: sunset in New York runs from 16:31 on 21 December to 20:30 on 21 June. A fixed alarm for golden hour is wrong within two weeks and useless within a month. Risetime sets an alarm on the sun's angle rather than on a clock time, and the angle is what actually defines those windows.
- Which sun angle matches golden hour, blue hour and astronomical night?
- Golden hour: +6° in the evening, −4° in the morning. Blue hour: −4° in the evening. Astronomical night: −18°, evening for when it starts and morning for when it ends. Definitions vary between photographers; these are the common ones, and the angle is adjustable. In the morning, golden hour begins at −4°, just after blue hour, and ends at +6°.
- How do I create the anchor?
- Open Settings → Anchors and press +. Keep the type on A solar angle, set your angle and choose morning or evening. Name it, pick a colour and save. Then, on the Alarms tab, set an alarm on it: at the anchor, or thirty minutes before to reach the spot.
- Does it work when I travel or have no signal?
- Turn on Auto-update location in Settings and your alarms follow you. Risetime computes the sun's position on the phone, with an astronomical library, and has no internet permission at all, so it cannot depend on a connection: airplane mode, a canyon, a boat, the alarm still knows when the light comes.
- Can Risetime warn me about moonrise or the full moon?
- No. It computes the sun only, offline: no moonrise, no Moon phase, no lunar calendar.