Privacy in the iPhone and Android apps
Astro Imaging Planner works out your night on the phone itself. It has no account, no ads, no analytics, no crash-reporting code and no tracking. The one thing it fetches from the internet is comet data from CEMeNt's own server, and that request carries nothing about you.
What stays on your phone
The app keeps these in its own storage on the phone:
- your place: its coordinates, the name you gave it, and whether it came from your location, was typed in, or is the default (Prague);
- your plan settings: minimum altitude, blocked directions, catalogues, sort order, comet brightness limit and hidden object types;
- your starred targets and saved sessions, with their names, places, nights, settings and dates;
- your theme and whether Dark red mode is on;
- the latest copy of the comet data, so the app still works without a signal.
None of it is sent to us or to anyone else. Deleting the app deletes it. Your phone's own backup, to iCloud or to Google, may include it, under your account and your backup settings.
Your location
The app asks for permission to use your location only when you tap Use current location in the Location sheet. It then reads your position once: a recent fix the phone already has, or a new one within 15 seconds, after which it gives up. The coordinates are stored on the phone as your place; they are never sent anywhere and are not looked up as an address.
You can type coordinates by hand instead, which needs no permission at all. Until you choose a place, the app uses Prague.
Comet data, the one connection
To list comets, the app downloads two files from CEMeNt's server:
https://api.cementcz.eu/, the orbits of the active comets;https://api.cementcz.eu/?obs=1, their recently observed brightness.
It fetches them when it starts and its copy is more than six hours old, when you tap Calculate with an out-of-date copy, and when you retry or pull to refresh, whether or not Comets is selected in your catalogues.
The requests carry nothing about you: no location, no identifier and no cookie. The only thing they say is the app's name and platform, ImagingPlanner/1.0 (iOS) or (Android), in the User-Agent header.
The server is a Cloudflare Worker that collects comet data from COBS, the Comet Observation Database, once a day. Like any web server, it sees the internet (IP) address a request comes from. Cloudflare keeps a log of the requests for at most seven days, and that log may include the address. We use it only to put faults in the comet feed right.
Nothing else is fetched. The survey images and the object texts are part of the app, and the links in Settings open your browser. If you allow it in your phone's settings, Apple or Google may pass on anonymous crash reports, as they do for any app.
This website
This page covers the apps. The planner and the object guide in your browser are part of cementcz.eu, and the site's privacy and cookies page covers them.
Changes and questions
If an update starts to use data in a new way, this page will say so before the update is released, and the date below will change. For questions, use the contact address on the app's App Store or Google Play listing.
Last updated .