SidereoPrivacy Policy
Last updated 30 August 2026
Sidereo is an astronomy app for iPhone. It has no accounts, no sign-in, and no server of its own. Nothing you do in the app is sent to us, because there is nowhere for it to be sent. This page describes exactly what stays on your phone and the few requests that leave it.
What we collect
Nothing. We operate no servers, no database and no analytics. We have no way to identify you, and we receive no information about you or your use of the app. Sidereo contains no analytics SDK, no advertising SDK, and no third-party tracking of any kind.
What stays on your device
Your favourites, observation logs, discovered-object list, equipment, settings and any photos taken in the app are stored locally using Apple's on-device SwiftData framework. They are not uploaded anywhere. Deleting the app deletes them.
Photos you choose to analyse, and any in-app guidance based on them, are processed on the device.
Requests that leave your device
Sidereo computes astronomical positions locally and works fully offline. A small number of optional features fetch live data from third parties. Each is listed below with exactly what it receives. We have no relationship with these providers, receive nothing back from them, and none of these requests carries an account, identifier or device ID.
| Service | Used for | What it receives |
|---|---|---|
| Open-Meteo | Weather and cloud forecast for observing | Your location coordinates. No identifier is attached. |
| NOAA SWPC | Aurora activity (planetary K-index) | Nothing about you — a fixed public data file. |
| CelesTrak | Satellite orbital elements, at most once a day | The catalogue number of the satellite. Nothing about you. |
| wheretheiss.at | Current ISS position | Nothing about you. |
| Wikipedia | Summary and photograph of an object you tap | The name of that object. Nothing about you. |
| NASA | Astronomy news feed | Nothing about you — a public RSS feed. |
As with any internet request, these providers necessarily see the IP address the request comes from, and each has its own privacy policy. Every one of these features is optional: with no network connection, Sidereo still computes the sky, and every object ships with its own offline description.
Location
Sidereo uses your location to work out what is above you right now. It is used on the device for every astronomical calculation, and it is not stored by us or transmitted to us.
The one exception is the weather forecast described above: to return a forecast for where you are, Open-Meteo is sent your coordinates. If you would rather that never happened, you can set a manual location in the app instead of granting GPS access, or leave the weather features unused.
Camera, motion and photos
The camera is used to draw the sky over the live view and to frame astrophotography shots. Motion sensors are used to know which way the phone is pointing. Photo library access is used to save what you create and, if you choose, to read a photo you ask the app to analyse. None of this data leaves the device.
Purchases
Subscriptions are handled entirely by Apple through StoreKit. Sidereo never sees or stores your payment details. Apple's own privacy policy governs that transaction.
Children
Sidereo is not directed at children under 13 and collects no personal information from anyone.
Changes
If this policy changes, the date at the top of this page changes with it, and the previous version is replaced here. There is no mailing list to notify, because we hold no addresses.
Contact
Questions about privacy: support@sidereo.app.