SSI Astronomy Planner

SSI Planner is the must-have tool designed by and for passionate deep-sky astrophotographers.

Simplify your imaging session planning with a powerful set of tools in a modern, smooth interface:

Light pollution maps and image packs (low-res mode available to avoid heavy downloads) for your targets in OFFLINE MODE — download them in the app to use the planner on the go, without any network connection.

*******************
• OFFLINE MODE: Search for targets even without a network connection. Set GPS coordinates for your location (city name only works in online mode). Target images are displayed even offline.
*******************

• SESSION PLANNER: Visualize optimal targets and their altitude curves, meridian transit times and Moon impact — tailored to your skill level, location (Bortle scale) and imaging setup.
• FULL CATALOG: Explore thousands of objects (Messier, NGC, IC, Sharpless, Arp, Abell, Hash and more) with smart search and filters by type (galaxies, nebulae, clusters).
• SKY FRAMING: Easily locate your target within its constellation in the sky.
• FOV CALCULATOR: Simulate your field of view based on your sensor and focal length to perfectly frame your targets.
• ASTRONOMICAL WEATHER: Check cloud cover and seeing forecasts for your GPS coordinates.
• EPHEMERIS: Track Moon phases and total darkness windows (astronomical night).
• EXPORT: PNG, PDF (online only), N.I.N.A. (Sequence & Target), ASIAIR (Plan), EKOS (Scheduler & Sequence) and APT (XML Plan).
• NEWS: Latest astronomy news.
• GUIDES: Handy references to understand astrophotography terminology.
• Astrophotographer galleries via Astrobin.

*******************
• NEW – SSI SENTINEL (optional online service): your observing assistant. Save your sites and projects (target, planned exposure time per filter): every day, our servers cross-check weather, Moon and the altitude of your targets to tell you whether the night is favorable (GO/NO-GO). Progress tracking per filter. Requires an account, also usable on stellarskyimager.fr.

Why a subscription when the app is paid? Buying the app gives you the complete SSI Planner, with no subscription, offline included, with all its updates: nothing you have bought becomes paid. Sentinel is a separate service running permanently on our servers (weather data, daily calculations, sending alerts), hence an optional subscription:
• Free: 1 site and 1 project, evening verdict available in the app.
• Premium (monthly or yearly, 30-day free trial): unlimited sites and projects, evening alerts (push and e-mail), weekly digest, 14-night calendar and full leaderboard.

FOUNDING MEMBER OFFER: to thank the app's users, Premium access to Sentinel is offered for the entire service operating life, to be activated from the app before November 15, 2026.
*******************

* Multilingual: French, English, German, Spanish, Italian and Chinese.
* Built-in night vision mode.

Best experienced on mobile.

SSI Planner is ad-free and fully respects your privacy. Prepare your setup, launch your sequence and let the magic of the cosmos unfold!

The app is regularly updated — we welcome your suggestions and bug reports.

Recent changes:
More reliable Sentinel project thumbnails. Sky images come from third-party services (CDS Strasbourg, NASA) that can be temporarily unavailable, as in recent days. When they are down, the app now shows the images from the offline pack installed on your device instead of blank thumbnails.