Support

Answers, and a
real reply.

Most questions are answered below. If yours is not, write to us — OwlPlot is made by one person, so the reply comes from someone who knows the code.

Email

support@owlplot.com

The numbers

What the app is telling you

How accurate are the sunrise and sunset times?
They are calculated from your exact coordinates, with atmospheric refraction accounted for, and are accurate to the minute. What you actually see can differ where terrain gets in the way — a ridge or a row of buildings moves your horizon, and the sun disappears behind it before it sets.
How is the photography score calculated?
It starts at 100 and deducts for cloud cover, precipitation chance, visibility and wind, then reads the result against the light conditions at that time. The app shows the biggest deduction as the reason, so a 60 tells you it is cloud rather than leaving you to guess. You can change how much each factor counts in Settings if your work weights them differently.
What is the difference between golden hour and blue hour?
Golden hour is when the sun sits low — roughly 6° above the horizon to 4° below — and the light is warm and soft. Blue hour is the band after that, with the sun 4° to 6° below the horizon: no direct sun, a deep blue sky, and the ambient light low enough that city lights read. OwlPlot gives both, morning and evening.
What are civil, nautical and astronomical twilight?
Three named stages as the sun drops further below the horizon: civil (to 6°) still has usable ambient light, nautical (to 12°) is where the horizon becomes hard to see, and astronomical (to 18°) is where the sky is dark enough for deep-sky work. The Milky Way and dark-sky windows are built on the astronomical band.

Sky

Moon, Milky Way and the AR view

How does the AR sky view work?
It uses the camera and the device sensors to place the sun, moon, planets and the Milky Way band on the live scene in front of you. Point the phone at the ridge you plan to shoot over and you can see whether the moon clears it. There is a time scrub, so you can drag forward and watch the path move without waiting.
Why does the AR view seem slightly off?
It leans on the compass, which is affected by nearby metal, magnets and phone cases with magnetic mounts. Move away from vehicles and railings and, if it is still off, calibrate the compass by moving the phone in a figure eight. The app also lets you nudge the heading manually.
When is the Milky Way core actually visible?
The app gives the window where the core is above the horizon and the sky is astronomically dark at the same time — which is what matters and is usually much shorter than the rise-to-set span. It varies with latitude and season, and there are months at high latitudes with no window at all.
How does the aurora forecast work?
It reads NOAA’s Kp index against your latitude, so the alert fires when the activity is high enough to be worth stepping outside where you are, rather than whenever Kp rises anywhere.

Dark skies

Sky darkness and light pollution

What is the Bortle class OwlPlot shows me?
The Bortle Dark-Sky Scale rates a sky from 1 to 9 by what you can actually see. Class 1 is pristine — the Milky Way casts shadows. Class 4 is a rural-suburban edge where the Milky Way is visible but washes out near the horizon. Class 9 is an inner city, where only the Moon, planets and a handful of bright stars survive. For a photographer it sets your noise floor: at Bortle 2 you can expose long at low ISO, while at Bortle 7 the skyglow fills the sensor before your subject does.
Where does OwlPlot get it from?
A light-pollution map bundled inside the app, so it works offline with no account and no lookups. It is built from the VIIRS Day/Night Band annual composite — a satellite instrument that measures light leaving the ground at night — at a resolution of about 4.6 km.
Is it measured or estimated?
Estimated, and we would rather say so plainly. The satellite sees light leaving the ground; what matters to you is the brightness of the sky above your head. Those differ: a valley 30 km from a city emits almost nothing itself but still sits under that city’s glow. OwlPlot models that spill by spreading each source’s light over a 250 km radius before working out a class. It is good to about one Bortle class. If you know a spot better than the model does, set the value yourself and yours wins.
Does light pollution change my Photography Score?
No, deliberately. The 0-100 score answers one question — are conditions good right now — and it moves with the weather. Light pollution is a fixed property of the place, not a condition. If we folded it in, a city user’s score could never rise no matter how perfect the night, and scores would stop being comparable between places. It would also be poor advice: clear, still evenings in a city are excellent for plenty of photography.
So what does it actually change?
Two things. It tunes the ISO in Tonight’s Recipe, because a brighter sky means less usable exposure before skyglow swamps the frame. And it feeds the Milky Way visibility rating, which is the one that matters most: sky darkness is arguably the single biggest factor in whether the galactic core is visible at all. A moonless, perfectly timed night still shows you nothing from a city centre, and the rating now reflects that. It also sets how many stars are drawn on the Today sky canvas.
Can I turn it off or correct it?
Both. Settings has an "Estimate sky darkness" switch — turn it off and nothing is estimated, while any values you set by hand are kept. You can also set the Bortle class on any individual saved location, and a value you set always beats the estimate. Saved spots show which is which: an estimated class is labelled as estimated.
Why does a spot show no value at all?
Either the estimate is switched off, or the location is outside the data. VIIRS covers 75 degrees North to 65 degrees South, so the far Arctic and Antarctic have no reading. When sky darkness is unknown OwlPlot applies no adjustment at all rather than guessing one.
Who made the data?
The VIIRS nighttime lights product is produced by the Earth Observation Group at the Payne Institute for Public Policy, Colorado School of Mines (Elvidge, Zhizhin, Ghosh, Hsu and Taneja, 2021). We credit it in the app under Settings. The 1-9 scale itself is John Bortle’s, first published in Sky & Telescope in 2001.

Coast

Tides, swell and surf

Where does the surf and tide data come from?
Marine forecasts come from Open-Meteo, and water temperature from the nearest NOAA buoy when one is reporting it. Some spots also carry a calibration built from what people at that beach reported seeing.
How far ahead does the forecast go?
Ten days. Pick a day and OwlPlot keeps the hour you were already looking at, so switching from today to Thursday does not throw you back to 9am.
Why does the wave height scale change?
The scale steps to fit the conditions rather than using one fixed maximum. A half-metre day and a five-metre day both need the full height of the chart to be readable — a fixed axis would flatten the small day into nothing.
What happens to a surf report I submit?
It is stored without anything that identifies you. There is no account, and the app does not attach a device identifier to what it saves — the coordinates are rounded to about 110 metres and what remains describes the sea, not a person. Reports are used to calibrate the forecast at that spot.
Is OwlPlot safe to rely on for going in the water?
No. It is a planning tool for photographers, and the marine data is a model forecast, not an observation. Conditions at the water change faster than any forecast updates. Check local conditions and warnings before you go in.

Devices

Where it runs

Is OwlPlot available on Android?
Yes. OwlPlot is on both the App Store and Google Play, built natively for each rather than wrapped.
Does it work offline?
The astronomy does. Sunrise, sunset, golden and blue hour, moon phase and position, and the Milky Way windows are all calculated on the device and need no connection. Weather, the photography score, tides, swell and aurora are live data and need one.
What does the Apple Watch app show?
The morning and evening light windows for your current spot, in that spot’s own time zone — so it stays right when you travel.
Are there home screen widgets?
Yes, showing tonight’s score and the next light window. Golden hour also runs as a Live Activity on the Lock Screen and Dynamic Island as it approaches.
Can I change which tabs appear?
Yes. Settings has a tab bar editor, so you can swap a tab you never open for one you do — a coastal shooter can put Surf where AR Sky was.
How do I switch between metric and imperial?
Settings, then Units. Metric gives km, km/h and °C; imperial gives mi, mph and °F. Wave heights follow the same setting, in metres or feet.

Privacy

What leaves your device

Why does the app want my location?
To calculate the sun, moon and sky for where you are. The calculation happens on the device — your coordinates are not sent to us for it. You can decline and search for any location by name instead; everything works the same way.
Can I turn analytics off?
Yes, in Settings. In the EU and UK analytics are off until you turn them on; everywhere else they are on by default and can be switched off at any time.
Do I need an account?
No. There is nothing to sign up for. Saved locations and shot plans live on your device.
Is any of this paid?
No. Every feature is in the free app — no subscription, no tier, no ads.

Troubleshooting

When something is not working

Location is not updating
Check that location permission is granted. On iOS: Settings → Privacy & Security → Location Services → OwlPlot, set to "While Using the App". On Android: Settings → Apps → OwlPlot → Permissions → Location.
Weather or tide data will not load
Both need a connection. Pull down to refresh. If it keeps failing, the upstream forecast service may be briefly unavailable — the astronomy keeps working meanwhile.
Notifications are not arriving
Confirm notifications are allowed for OwlPlot in system settings, and that the specific alert is enabled in the app. On Android, check that battery optimisation is not restricting OwlPlot in the background.
The app crashes or freezes
Update to the latest version first, then restart the device. If it continues, email us with what you were doing when it happened and which device you are on — that is usually enough to find it.

Still stuck?

Tell us what you were doing and which device you are on. That is usually enough to find it.

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