Name: Aurora Score– Northern Lights for Eye & Camera
Rating: 5 (1 reviews)
Author: RunnerUp

A live northern lights nowcast and forecast for your exact location. The app gives a 0–100 score for the chance of seeing the northern lights with the naked eye or a (phone) camera, based on live space weather data.

The score is based on live space weather data, as well as data at your current location:

• Live Kp: the half-hourly Hp30 index from GFZ Potsdam (NOAA's Kp as a backup), updated with the live solar wind (Bz, speed), corrected for when it reaches Earth.
• Hemispheric Power: the energy input of the aurora.
• The ring current (Dst index): in big storms it pushes the auroral oval further south.
• Your magnetic latitude and where the auroral oval sits at this time of night.
• Darkness where you look (not just overhead), moonlight and cloud cover.
• Cloud cover from four weather models (GEM, ECMWF, GFS and ICON), averaged. When they disagree, the app tells you the clouds may clear.
• Light pollution at your location, from NASA satellite night-light maps (Auto), or one of four levels you choose.

Separate scores are calculated for seeing the aurora with your eyes and for capturing it with a camera, as a camera picks up fainter aurora. On the Next 18 hours, Why and Next 3 nights pages, START (or a tap) switches between the two.

Features in the app:

• Glance: a bar from 0–100, matching the score.
• Main screen: separate scores for eye and camera, what is limiting the score right now, and the best time to look.
• Next 18 hours: the score for each hour.
• Why this score: bars for aurora strength, darkness, clouds, moon and light pollution, and what holds the score back most.
• Details: a compass showing where to look, plus the current space weather with ratings and trends.
• Next 3 nights: the best score and time for tonight and the next two nights, and what holds each night back: clouds, moon, twilight or the Kp it would need.
• Next 3 days: the Kp forecast, with the levels needed at your location to see the aurora by eye or camera.
• Alerts (hold UP): choose the naked-eye or camera score and a threshold. Options for quiet (sleeping) hours, an alert when the aurora moves overhead, early alerts when the solar wind on its way is expected to push the score over your threshold, and an afternoon heads-up when tonight's best time reaches your threshold.
• Night-red (hold UP): dims the screen to red at night to protect your night vision.

Works in both hemispheres. Refreshes every 15 minutes after dark and hourly by day. Needs a phone connection (Garmin Connect app) for data. For your location the app uses the watch's GPS.

Space weather is hard to predict: the score is an informed estimate, not a guarantee.

Aurora Score is free, without ads or subscriptions.

Support: use "Contact Developer" on this store page. Questions and bug reports are welcome.

Data: NOAA Space Weather Prediction Center. Hp30 index: GFZ Potsdam (CC BY 4.0). Dst index: WDC for Geomagnetism, Kyoto. Weather data by Open-Meteo.com (CC BY 4.0). Light pollution: NASA Black Marble (VIIRS).

Privacy
Aurora Score has no account, no ads and no analytics, and the developer collects no personal data.

• Your exact location stays on your watch. The watch gets its data from the app's own server, sending your location rounded to 0.1 degree (about 10 km), through your phone's connection. The server rounds it again to about 25 km to look up the cloud forecast at Open-Meteo, keeps that cell for at most 3 hours as a cache key, and never logs it.
• If the server can't be reached, or has no cloud forecast for you at that moment, while the app is open, the watch asks the original sources directly: Open-Meteo for the clouds (with the location rounded to 0.1 degree), NOAA and GFZ Potsdam for space weather (no location).
• Every web request shows your phone's IP address to the server it goes to, as usual.
• Settings and the last data are stored on the watch only.