/ apple · Coming soon
Sidereo.
An offline astronomy guide for iPhone.
Sidereo is an astronomy and astrophotography app for iPhone that computes the sky around you entirely on-device — the Sun, Moon, planets, stars, satellites and comets — from published models (Meeus' series, Keplerian elements, and an SGP4 propagator for satellites), so it works with no network connection at all. Point the phone at the sky to find and shoot an object, tap it for a summary and photo pulled from Wikipedia, and let a daily-refreshed comet and satellite catalogue and an optional live cloud-cover overlay round out the picture. There are no accounts: favourites, observation logs, discovered objects and gear stay on the device and are deleted with the app.
iPhone
/ 01 — Features
What it does.
- / 01Fully offline positions — Sun, Moon, planets, stars, satellites and comets computed on-device from published astronomical models; no network connection needed.
- / 02Point-and-find sky view — aim the phone at the sky to locate and photograph objects, with a Verify Compass step that corrects for magnetometer drift.
- / 03Daily orbital-element refresh — comet and satellite data from CelesTrak and the Minor Planet Center, served through Sidereo's own feed.
- / 04Wikipedia lookups — tap an object for a summary and photograph, fetched on demand.
- / 05Live weather overlay — optional cloud-cover and forecast from Open-Meteo, layered over the sky view.
- / 06Realistic sky, not oversaturated — a Bortle sky-darkness setting shows only what is actually visible from where you are.
- / 07Red-light mode — covers the whole app to preserve night vision outdoors.
- / 08No accounts, ever — favourites, observation logs, discovered objects and gear stay on the device.
- / 09Sidereo Pro — an optional monthly, yearly or lifetime purchase, handled entirely by Apple through StoreKit.
/ 02 — Legal & Support