Ptolemy Privacy Policy

Effective October 26, 2026

Ptolemy is a mobile sky map and stargazing guide published by Third Stone Software ("we", "us"). This policy explains what information the app handles and why.

The short version

  • There are no accounts, no sign-up and no log-in.
  • There are no ads, and we don't run any analytics or tracking.
  • Your location is used on your device to work out the sky above you. The only place it is sent is the cloud forecast service, rounded to about 11 km (7 miles).
  • The camera picture is shown live behind the sky map. It is never recorded, saved or sent anywhere.
  • Your settings, reminders and saved places stay on your device. We never receive them.

Location

With your permission, Ptolemy reads your device's approximate location to show the stars and planets as they appear from where you are, to correct the compass for magnetic declination, and to time rises, sets, eclipses and satellite passes. These calculations are done on your device. If you don't allow location access, you can choose a city or enter coordinates instead.

So that the home-screen widget and space station alerts stay up to date when the app is closed, the app saves the last place it showed on your device. It does not track your location in the background.

When Cloud forecast for tonight is on, the app sends the latitude and longitude of the place you're viewing, rounded to one decimal place (roughly 11 km or 7 miles), to Open-Meteo to get the hourly cloud, temperature, dew point and wind forecast. You can turn the forecast off in Settings.

Camera

If you turn on Camera, the app shows the live camera picture behind the sky so you can match stars to the landscape. The picture is displayed only. It is not recorded, saved or sent anywhere, and no audio is captured.

Motion sensors

The app reads the compass, accelerometer and gyroscope so the sky map follows where you point your phone. This sensor data is used on your device and is never stored or sent.

Online data the app downloads

To stay current, the app downloads public astronomy data. These requests don't include your location or any personal information. As with any internet request, the service sees your device's IP address.

Telescope control

If you connect a telescope mount, the app talks to it directly over your local Wi-Fi network, using the address you enter. These commands go only to your mount and never to us.

Information stored on your device

Your settings, chosen place, reminders, horizon profile, telescope setup, the objects you've seen, and cached downloads (orbits and forecasts) are saved in the app's private storage on your device. Reminders and space station alerts are scheduled as notifications on your device. The guided tour is read aloud by your device's text-to-speech engine. None of this is sent to us. Uninstalling the app deletes all of it.

Sharing

Share this sky makes a picture of the current view, labelled with the place and time, and opens your device's share sheet. Nothing is shared unless you choose an app to share it with.

What we don't do

  • We don't collect, sell or share your personal information.
  • We don't show ads or run analytics or tracking in the app.
  • We don't ask for access to your contacts, microphone, photos or files.

Children

Ptolemy is not directed to children under 13, and we do not knowingly collect personal information from them. If you believe a child has provided personal information through the app, contact us and we will help.

Changes to this policy

If this policy changes, we will update it on this page and change the effective date above.

Contact

Questions about this policy or your data: paul.henninger@thirdstone.com.