In short: Deep Sky Scanner does its work on your device. Your location and the direction you're pointing your phone never leave it. The app has no account, no analytics, and no advertising.
Deep Sky Scanner needs two pieces of information from your device to work at all:
Neither of these is transmitted anywhere. There's no server that receives your location or orientation, because the app doesn't have one for this purpose.
The app fetches deep-sky object data (names, coordinates, magnitudes) from a public astronomical catalog (GAVO's OpenNGC service) so it can show you what's nearby. This is a one-way, anonymous request for catalog data — it does not include your location, your device identity, or anything else about you. If you're offline, the app falls back to a catalog copy stored on your device.
Any preferences or logged observations you save in the app stay in local storage on your device. Uninstalling the app removes them.
If this policy changes, the "last updated" date at the top of this page will change with it. Continued use of the app after an update means you accept the revised policy.
Questions about this policy or how the app handles data can be sent to chris.eddy.email@gmail.com.