Sky42 privacy, in plain language.

Sky42 is standalone and offline-first by design. This page explains the two pieces of network activity the app has, and what happens when you use this website.

This document applies to the Sky42 website at demahub.com/sky42 and the Sky42 desktop app.

Sky42 works fully offline once its catalogues are on disk — it does not depend on remote services to run.
The app sends one anonymous usage report per session: app version, operating system, OS language, and whether the session ended normally or crashed.
Nothing about what you observe is sent: no location, no searches, no sky view, no file names.
The only other network call the app makes on its own is a silent, at-most-weekly check of one small file, to see if a newer version exists.
Orbital-element updates and catalogue downloads only happen when you explicitly ask for them.
If you contact us directly, we use your message only to answer the request.

Who is responsible

Sky42 is published by Davide De Martin through DemaHub.

Contact: info@demahub.com

Last updated: 2026-09-23

Anonymous usage report

Sky42 sends one anonymous event per app session to https://www.demahub.com/sky42/usage/analytics.php. It tells us how many sessions and devices use Sky42, on which systems and languages, and how often it crashes — nothing more.

What is sent A random device identifier, a random session identifier, the session start time, the app version, the operating system family (for example mac or windows-11), the OS language (for example it), and how the session ended: normally, unexpectedly, or with a crash. For a crash, a short summary is added: the error kind (for example "Segmentation fault" or an exception type), up to ten code locations inside Sky42 or its libraries, and a hash that groups identical crashes.
What is not sent Your observing location, date and time settings, searches, the part of the sky you look at, file names, folder paths, error messages, and the raw crash log. Code locations are reduced to the file inside Sky42 or a library and a line number; any path on your computer is removed before anything is written for sending.
How the identifier works The device identifier is a random number created the first time Sky42 runs and stored in your user folder. It is not derived from your hardware, your account, or your network, and deleting the Sky42/telemetry folder creates a new one.
When it is sent When Sky42 closes, and again at the next start for anything that could not be sent, including the report of a session that crashed. Events waiting to be sent are kept as small files in the same folder, at most fifty.
IP address The endpoint uses the request IP address transiently, in hashed form, for rate limiting. The usage database does not store it.
Legal basis Legitimate interests (Article 6(1)(f) GDPR): improving software quality, finding crashes, and knowing which platforms and languages to support. Only pseudonymous identifiers are processed.
Retention Usage records are deleted from the dataset 24 months after they are received.
Turning it off Untick Send an anonymous usage report in Preferences…, under the ⋯ menu, and nothing is recorded or sent from the next start on. Starting Sky42 with --no-telemetry does the same for one session.

The update check

Sky42's other unsolicited network activity is the update check: a plain GET request to https://www.demahub.com/sky42/version.json, at most once every seven days, and only to read the published version number, release date, changelog text, and a download link.

What is sent An ordinary HTTPS request for a static JSON file. Sky42 does not attach the device identifier, a usage history, or any personal data to this request — it is the same request your browser would make to read the file.
What comes back A version number, a release date, changelog text, and a download URL. The app checks that the URL's host is one it trusts (demahub.com, www.demahub.com, or cdn.demahub.com, over https) before ever offering it — a manifest that failed that check is rejected outright, not partially trusted.
Nothing is downloaded or installed automatically Sky42 does not self-update. If a newer version exists, the app tells you and a button opens this website in your browser — the install, if any, is something you do yourself.
Turning it off The --no-update-check command-line flag disables this check entirely.

Catalogue and orbital-element downloads

Sky42's catalogue manager downloads star, deep-sky and other catalogue packs — the Gaia star tiers, for example — from https://www.demahub.com/sky42/, reading the list of available packs from packs.json. Refreshing minor-planet and comet elements downloads MPCORB and CometEls directly from the Minor Planet Center (minorplanetcenter.net). Both happen only when you ask for them, and both are ordinary HTTPS requests for public files: no device identifier or usage data is attached. They are not triggered by ordinary use of the app.

Website and download pages

When you visit the Sky42 website or download page, standard technical request data may be processed by the hosting environment to serve the page, secure the service, and troubleshoot abuse or failures — for example IP address, user agent, requested URL, and timestamps. These are ordinary web server logs, separate from anything the desktop app does.

Direct contact, bug reports, and feature requests

If you contact us by email, we process the information you send so we can respond, follow up, and keep a record of the conversation if needed for support or product decisions. This normally includes your email address, the content of the message, and any attachments or diagnostic details you choose to send — such as the text produced by the About dialog's "Copy details" button.

Your choices

Usage report Turn the usage report off in Preferences…, or run Sky42 with --no-telemetry for a single session. You can also object to this processing under Article 21 GDPR by writing to info@demahub.com with the contents of the device_id file in the Sky42/telemetry folder; we will delete the records associated with it.
Update check Run Sky42 with --no-update-check to disable the weekly check entirely.
Privacy requests You can ask for access, correction, or deletion of data related to your direct contact history by writing to info@demahub.com.

Changes to this policy

This page will be updated if Sky42 changes what its usage report contains, adds a network-dependent feature, or a different website processing step. The latest version will always be published at this URL, and any change to what is sent will be described here before or as it ships.