FAQ
Section 1: Using NightVis
Q: How do I save my favorite imaging locations?
A: Search for a location or use the GPS button, then click the Star icon (★) to save it. Click the pencil icon next to the location name to give it a custom label like “Backyard” or “Dark Sky Site”.
Q: How do I change the time or date format?
A: Click the Gear icon (⚙) in the top right corner. You can toggle between 12h/24h time and MM/DD or DD/MM date formats. You can also turn on “Red Light Mode” to preserve your night vision in the field.
Q: Where is my data stored? Can I use my settings on another device?
A: Your settings and saved locations are stored in your browser's local storage — they are never sent to a server. You can back them up via Gear icon (⚙) → Export/Import.
If you enable push notifications, your notification preferences and selected location coordinates are sent to the server so it can send timely alerts to your device. No personal data (name, email, IP, etc.) is stored — only what's needed to deliver the notifications you requested. Notifications can be disabled at any time in Settings.
Q: Why does the Cloud forecast go out 16 days, but Seeing only goes out 3 days?
A: We pull data from different models. Cloud cover and humidity (Open-Meteo) provide reliable forecasts up to 16 days. Atmospheric Seeing (7Timer!) is much harder to predict and only stays useful for roughly 3 days. Beyond that, Seeing values are estimated from cloud cover and humidity.
Q: How do notifications work?
A: NightVis sends you a push notification when conditions look good for imaging — even when the app is closed. Go to Settings (⚙) and enable “Notify when conditions are good”. You can choose what triggers a notification: a minimum score threshold, a verdict level (Great/Medium), or custom cloud and moon limits. You can select both Deep Sky and Planetary forecast types, set how many days ahead to check (1-5), pick one or more saved locations, and set one or more check times (e.g. 4pm and 8pm). Use the “Test Notification” button to verify notifications are working.
How it works: A server checks the weather at your configured times and sends a push notification if conditions meet your threshold. This works even when the app is completely closed. Check times are in your device’s local timezone. Notifications arrive within approximately 15 minutes of your configured time.
Requirements: Desktop & Android: Notifications work in Chrome, Edge, and Firefox — no installation needed, just grant notification permission. iOS (iPhone/iPad): You must install NightVis as a PWA. Open in Safari, tap the Share button, select “Add to Home Screen”. iOS 16.4+ supports Web Push from installed PWAs — standard Safari and Chrome tabs on iOS do not support push notifications.
Section 2: The Math & Scoring
Q: Where does NightVis get its weather data?
A: We combine data from multiple trusted sources. Hourly cloud cover, humidity, and visibility are provided by Open-Meteo. Atmospheric Seeing and Transparency are fetched from the 7Timer! Astro API.
Q: Why are there separate toggles for Deep Sky and Planetary?
A: Because they require completely different weather conditions! Deep Sky imaging requires a dark sky, meaning the Moon is heavily penalized in our scoring algorithm. Planetary imaging ignores the Moon completely, but uses “Seeing” (atmospheric stability) as a strict bottleneck multiplier.
Q: What is “Seeing” and “Transparency”?
A: Transparency measures the clarity of the air (free of smoke, dust, or high humidity) which is vital for faint nebulae. Seeing measures atmospheric turbulence on a 1 to 8 scale (1 being perfectly still, 8 being a boiling mess). If Seeing is 5 or worse, planetary images will be blurry no matter how clear the sky looks.
Q: How is NELM (Naked Eye Limiting Magnitude) calculated?
A: NELM measures the faintest star you can see with your bare eyes. NightVis shows your “Max” NELM based on your location's Bortle class. The “Current” big blue number is adjusted downward in real-time based on current Moon illumination, Moon altitude, and cloud cover.
Q: Why does my location show “No astronomical darkness”?
A: If you live at a high latitude during the summer, the sun never dips more than 18° below the horizon. The sky stays in a state of perpetual twilight. NightVis detects this, switches its forecast window from “Darkness” to “Sunset-Sunrise”, and flags it because true broadband deep-sky imaging will be severely limited.
Q: What is the difference between a “Bad” and “No” verdict?
A: A “Bad” score is between 35 and 59—it's not great, but you might still get some testing or narrowband data. A “No” means the final astro score dropped below 35/100. This happens if a specific bottleneck is triggered (like a 90%+ illuminated Moon for Deep Sky, or terrible Seeing for Planetary). Check the “Why No?” button for the exact mathematical breakdown!
Q: How does wind speed affect my score?
A: Wind ruins guiding and long-exposure astrophotography. NightVis calculates the average wind speed during the night window from Open-Meteo data. In Settings you can set your wind limit (default 25 km/h) and unit preference (km/h or mph). If the forecasted wind exceeds your limit, the score is penalized proportionally — the worse the wind, the heavier the penalty. Wind penalty is applied on top of all other scoring factors and is clearly shown in the “Why” breakdown.