Aurora Signal

Aurora Signal estimates whether the aurora borealis is likely to be visible where you are, by combining space weather, cloud cover, light pollution and the moon. There is no account, no login, and no server of our own. This policy explains the little data the app touches and where it goes.

Location Data

Aurora Signal requests access to your device location solely to:

Work out how far you are from the aurora oval, which is what makes the probability specific to you rather than generic
Fetch the cloud forecast for your area
Estimate the light pollution where you are standing
Find darker viewing spots near you and centre the map

Your coordinates are sent to Open-Meteo to retrieve the cloud forecast for your area, because a forecast cannot be fetched without saying where you want it for. Open-Meteo is a free weather API that does not require an API key and does not identify who is asking.

Everything else happens on your device. Light pollution is read from a map bundled inside the app, so no location is transmitted to work it out, and the space weather data is global and identical for every user, so no location is sent to retrieve it either. Your location is never sold, never shared with anyone else, and never used for advertising.

Notifications

Notifications are scheduled locally on your device by iOS. There is no push server, and no device token is generated or transmitted. If you turn notifications on, the alerts are composed on your phone from data your phone already fetched, and nothing about them leaves it.

Photos

Photographs you add to your sightings log are stored on your device and stay there. They are not uploaded, backed up to us, or transmitted anywhere. The app asks for camera and photo library access only so you can add them.

Data We Do Not Collect

No account or registration is required
No name, email, or personal identifiers are collected
No analytics or crash reporting SDKs are included — the app contains no third-party code at all
No advertising networks are used
No location history is kept; each reading is used and discarded

Purchases

Aurora Signal Pro is sold through Apple's In-App Purchase. Apple handles the transaction and we never see your payment details. The app asks Apple whether this Apple ID owns the subscription and stores nothing about you beyond that answer.

Third-Party Data Sources

Space weather comes from the NOAA Space Weather Prediction Center, a US Government public domain service, which receives no information about you. Cloud forecasts come from Open-Meteo, which receives the coordinates described above and nothing else. Light pollution is derived from NASA and NOAA VIIRS night-lights imagery, bundled into the app.

Children's Privacy

Aurora Signal does not knowingly collect data from children under 13.

Changes to This Policy

If this policy changes materially, the updated date at the top of this page will reflect the revision.

Contact

Questions? Email us at memo@hollowfieldco.com.