Privacy Policy
How AstroSat collects, uses and protects your information.
Last updated: 21 September 2026
AstroSat (“AstroSat”, “we”, “us”) is a free satellite-tracking web app run by one person in the Netherlands, who is the data controller for the purposes of the GDPR. It is not a business and takes no payments; see our Terms of Service. This policy explains what information we collect when you use AstroSat at astrosat.app, how we use it, and the choices you have. If you have any questions, contact us at christian.smartflux@gmail.com.
1. Information we collect
You can browse the globe, sky and solar system without an account. We collect information in the following ways:
- Account information — if you choose to sign in with Google or with an email address, we receive your name, email address and (for Google) profile photo. This lets us create your account and save your data.
- Content you create — the satellites you track and the custom constellations you build are saved to your account so they sync across your devices.
- Location — if you grant location permission, your device location is used in your browser to work out what is overhead and when satellites pass. It never leaves your device, with one exception: if you set up pass alerts or the calendar feed, we store it (to roughly 100 m) so we can work out your passes while the app is closed — see section 12.
- Usage & device data — we use analytics to understand how the app is used (pages/features viewed, device and browser type, approximate region derived from your IP address, and anonymous identifiers). This helps us improve AstroSat. Before you answer the analytics consent prompt, and if you decline it, this measurement runs in a cookieless mode: we receive aggregate counts only (such as how many people opened a page, the browser type and the approximate region from your IP address). No cookies are set, no identifier is stored on your device, and your visits cannot be linked together or back to you. See section 8.
- Local storage on your device — we store preferences (such as dark mode), a cache of public orbital data, and your sign-in session in your browser's local storage / IndexedDB.
2. How we use your information
- To provide and maintain the service and your account;
- To save and sync your tracked satellites and constellations;
- To understand usage and improve performance, reliability and features;
- To keep the service secure and prevent abuse;
- To send you the AstroSat Weekly newsletter, but only if you have explicitly opted in (see section 12);
- To comply with legal obligations.
Our legal bases (GDPR) are performance of our agreement with you (providing the app), your consent (e.g. location, optional analytics), and our legitimate interests in operating and improving a secure service.
3. Discontinued AI features
AstroSat used to offer three AI features — a per-satellite briefing, a Mission Control chat and a daily brief — which sent data to Anthropic (Claude) to generate text. They were withdrawn on 21 September 2026 and no data is sent to Anthropic any more.
Content those features already produced is still stored: chat transcripts and daily briefs remain private to your account, and satellite descriptions remain in a shared cache. None of it is personal data beyond what you typed into a chat yourself. Deleting your account removes everything held under it, as described in section 6.
4. Service providers we use
We rely on the following providers to operate AstroSat. They process data only as needed to provide their service to us:
| Provider | Purpose |
|---|---|
| Google Firebase / Google Cloud | Authentication, database, file storage, hosting and analytics |
| Microsoft Azure | Hosting our media-automation backend (n8n), used to produce our own social-media content. No user account data, messages or location are processed there. |
| Resend | Delivering the optional newsletter and its confirmation emails (see section 12) |
| CelesTrak / Space-Track | Public orbital (TLE) data source — no personal data involved |
5. Storage, international transfers & security
Your data is held by the providers above, whose servers may be located in the European Union and/or the United States. Where data is transferred outside the European Economic Area, it is protected by appropriate safeguards such as the European Commission’s Standard Contractual Clauses. We protect data with encryption in transit (TLS/HTTPS) and encryption at rest provided by our infrastructure providers, together with access controls and multi-factor authentication on our administrative accounts.
In the event of a personal-data breach that is likely to affect you, we will notify the relevant supervisory authority and, where required, affected users without undue delay.
6. Data retention & deletion
We keep your account information and saved content — including your tracked satellites, custom constellations, and any chat history and daily briefs left over from the discontinued AI features (see section 3) — for as long as your account is active. Those features are no longer reachable, so chats can no longer be deleted individually; email us and we will remove them. You can sign out at any time, and you can request access to, export of, or deletion of your account and data by emailing christian.smartflux@gmail.com. We will delete your data unless we are required to retain it by law.
7. Your rights
Subject to applicable law, you have the right to access, correct, delete, restrict or object to the processing of your personal data, to data portability, and to withdraw consent at any time. You also have the right to lodge a complaint with your local data-protection supervisory authority. To exercise any of these rights, contact us at the email above.
8. Cookies & similar technologies
AstroSat does not use advertising cookies. We use your browser’s local storage for app preferences and your sign-in session. Analytics identifiers to measure usage are only set after you accept the analytics consent prompt. You can clear this data through your browser settings at any time.
Measurement before consent. So that we can tell how many people visit AstroSat at all, our analytics provider (Google Analytics 4) runs in Google’s Consent Mode with analytics storage set to denied until you accept. In that state it sends cookieless pings: no cookie is written, no client identifier is created or stored on your device, and individual visits cannot be joined into a session or profile or linked to you. We rely on our legitimate interest in understanding aggregate traffic to our own site for this, and because no information is stored on or read from your device it does not require consent under the ePrivacy rules. If you accept the prompt, standard Google Analytics with a client identifier is enabled; if you decline, the cookieless mode continues. Advertising signals are disabled in both states.
AstroSat is protected by reCAPTCHA Enterprise, used solely to distinguish real app sessions from automated abuse (our legitimate interest in operating a secure service). The Google Privacy Policy and Terms of Service apply to it.
9. Children
AstroSat is not directed to children under 16, and we do not knowingly collect personal data from them. If you believe a child has provided us personal data, contact us and we will delete it.
10. Changes to this policy
We may update this policy from time to time. When we do, we will revise the “Last updated” date above. Significant changes will be highlighted in the app where appropriate.
11. YouTube API Services
Separately from the AstroSat app, we operate an automation that publishes original video content we create to a YouTube channel we own (youtube.com/@AstroSatApp), using the YouTube Data API (“YouTube API Services”). This automation authenticates solely as that channel’s owner — it does not access, collect, or process any other person’s YouTube account, videos, or data.
Our use of YouTube API Services, and any information obtained through it, complies with the YouTube Terms of Service and the Google API Services User Data Policy, including its Limited Use requirements. Data handled by Google/YouTube directly is governed by the Google Privacy Policy.
To review or revoke this automation’s access to a Google Account, visit Google Account → Security → Third-party apps with account access. To request deletion of any data associated with our use of YouTube API Services, contact us at the email below.
12. Newsletter & emails
We send two kinds of email. Service emails (sign-in verification, password resets) are part of providing the service and are sent to all account holders.
The AstroSat Mail (our newsletter) is entirely optional and is never switched on for you. You receive it only if you opt in explicitly — by ticking the newsletter box yourself in your profile settings, or by submitting your address to the subscribe form and then clicking the confirmation link we email you (“double opt-in”). We do not add existing account holders, waiting-list entries or anyone else to the newsletter without that separate, explicit consent. Our legal basis is your consent, which you may withdraw at any time.
Every issue contains a one-click unsubscribe link that works without signing in, and supports your mail app’s own unsubscribe button. Unsubscribing takes effect immediately, stops every email we send you other than service emails, and does not affect your account. To manage the newsletter we store your email address, the date and source of your consent, how often you asked to receive it, and whether your subscription is pending, confirmed or unsubscribed. If you subscribed without an account, you can ask us to erase that record entirely by emailing the address below. Newsletters are delivered by Resend (see section 4) and are only ever sent to verified or confirmed addresses.
Optional location. You may choose to share your approximate location so we can include the best visible satellite pass over your sky. We ask in three places, all of them optional and none of them a condition of subscribing: on the subscribe form, on the page you land on after confirming your subscription, and on the Email card in your profile. Your position is rounded in your browser to roughly 10 km before it is sent to us, so we never receive or store a precise location from these. We use it for nothing but calculating passes for your emails. You can have it removed at any time by unsubscribing or by emailing the address below.
Separately, if you set up the calendar pass feed or pass alerts, the location you give it is stored more precisely — to roughly 100 m — because a calendar entry states an exact time for an exact spot. It is the same stored location, so a feed you have set up will also be used for your emails. Deleting your account removes both.
13. Contact
AstroSat is operated by smartflux. For any privacy questions or requests, contact christian.smartflux@gmail.com. This policy is governed by the laws of the Netherlands.