Privacy Policy
This policy explains what Noctua Software Limited, trading as Stellarium Labs ("we"), does with personal data when you use our apps, our websites and the online services they rely on. It applies to all the products we publish under the Stellarium name. Last updated: 4 November 2026.
1. Who we are
Noctua Software Limited, trading as Stellarium Labs, a company incorporated in Hong Kong (Companies Registry number 1676103), Unit G, 15/F, TAL Building, 49 Austin Road, Kowloon, Hong Kong. We are the data controller. Privacy questions: [email protected]. Support: [email protected].
2. What stays on your device
The sky map, your settings, your observing lists, your location, the compass and motion sensors, the camera picture in the augmented reality view and the Bluetooth or Wi-Fi link to your telescope are handled on your device. We receive none of it, except the rounded position of section 3 (weather) and what you choose to sync with an account (section 5).
3. What our server sees when the apps or sites talk to it
Your network address. Our server sees the address of your device when an app or a site asks it for something (a starting position, the weather, account sync). We keep a request log for two weeks with the last part of the address removed. To limit abuse we also count requests per network address, app installation or account for at most a day. Sky data files are served by DigitalOcean’s content delivery network under its own terms. The desktop program Stellarium only asks us for the starting position below.
A starting position from your address. When an app or site has no position from your device, it asks our server for the city your network address belongs to, so the sky map can start somewhere sensible. The answer is computed from the DB-IP database on our server and not stored. You can set any location by hand.
Weather. The weather features ask our server for a forecast. The request carries your position rounded to a grid of about 25 km, which we do not store. Our server passes it to the forecast provider, Open-Meteo, and keeps the forecast in a cache for a few hours.
App verification. From time to time our mobile apps ask the platform (Google Play Integrity on Android, App Attest on iOS) for a proof that the app is genuine and send it to our server. The proof contains no personal data. On iOS it includes a key of the app, which we keep while the app is in use.
Purchases. Purchases are made through Google Play, the App Store or the Meta store. We receive from the store a record of what you bought and when, which unlocks it, never your payment details.
4. Usage statistics
Our apps on Android use Google Firebase Analytics and Remote Config. They send to Google: random identifiers of this installation, the advertising identifier of the device, the screens you open and your sessions, your purchases of the upgrade (product and price), your approximate location (country, city) from your masked network address, your country, language and time zone, your device model, platform and system version, and the app’s name and version. No precise location, no name or email. Google keeps the event data for two months and the identifiers while the app is installed; we keep aggregate reports. We use them to see which features are used and to test variants of the app’s screens.
Our apps on iOS and on VR headsets send no usage statistics.
Our websites, the web app included, use Google Analytics to count visits; we do not use Google’s advertising features and the event data is kept for two months. For visitors from the European Economic Area, the United Kingdom and Switzerland no analytics cookie is set: Google only receives, per page view, the page address and the browser type, without an identifier. Elsewhere Google Analytics uses cookies, which you can block in your browser.
Storage in your browser. The web app keeps your settings in your browser’s storage and, if you have an account, a copy of what you sync and your sign-in session, so that it opens with your data and works offline. This storage is needed for the service you use and serves nothing else. Your settings never reach us; what you sync does, as section 5 explains.
5. Your account
You can create an account in the web app to keep your observing lists, observations, equipment and places on our servers and see them on all your devices. An account needs only an email address; one not confirmed within a day is deleted. We then store:
- your email address and a scrambled form of your password;
- what you sync: lists, observations with their date and place, equipment, places;
- sign-in sessions, which expire after 90 days;
- for one hour the address of each sign-in or sign-up attempt, and for one day the address from which an account email was requested, to block abuse.
You can delete your account in the product. This deletes your data at once; backups keep a copy for up to 15 days, and one backup a month for up to a year.
6. Support
If you write to [email protected], we keep your email and our answer in our mailbox, hosted by Google Workspace, for as long as needed to help you.
7. Why we may use your data (legal basis)
- To provide what you asked for, under our terms of use: purchases, account and sync, weather, the starting position.
- Our legitimate interest in keeping the services working and safe, and in knowing how they are used: request logs, abuse limits, app verification, the usage statistics of section 4.
- A legal obligation, when the law requires us to keep or give data.
8. Who else sees data
Only the providers that work for us. They may use the data only to provide their service to us and must protect it at least as this policy does: Google (Firebase, Google Analytics, Google Play, Google Workspace for our mailbox and account emails), Apple (App Store, App Attest), Meta (Meta store), DigitalOcean (hosting and content delivery), Open-Meteo (weather). We never sell personal data and do not use it for advertising. We disclose data to authorities only when the law requires it.
9. Where data is kept
We work from Hong Kong. Our servers are hosted by DigitalOcean in the United States, and Google, Apple and Meta process data in the United States and elsewhere. For users in the European Economic Area, the United Kingdom and Switzerland, these transfers rely on the standard contractual clauses and data processing terms of those providers, which they publish and we can send you on request.
10. Security
Connections to our servers are encrypted. Passwords are stored hashed. Only the people who run the service can access the servers.
11. How long we keep data
| Data | Kept |
|---|---|
| Request logs, with the last part of the address removed | 2 weeks |
| Abuse counters (network address, app installation, account) | 1 hour to 1 day |
| Address of an account email request | 1 day |
| Unconfirmed account | 1 day |
| iOS app verification key | until unused for 90 days |
| Usage statistics, event data | 2 months |
| Account and synced data | until you delete the account, then up to 15 days in daily backups and up to a year in monthly backups |
| Sign-in sessions | 90 days |
| Support emails | as long as needed to help you |
12. Your rights
You can ask us what data we hold about you, have it corrected or deleted, restrict or object to its use, receive a copy, and withdraw a consent at any time. Write to [email protected]; we answer within one month. If you are in the European Economic Area, the United Kingdom or Switzerland you can also complain to your data protection authority.
13. Children
Our products are not directed at children and we do not knowingly collect personal data from a child. If you believe a child has given us data, write to [email protected] and we will delete it.
14. Changes
We may update this policy. For a change that matters to you, we will tell you in the app or on the site.