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.

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• 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.
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• 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.

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• 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.
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* 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:
• Redesigned target cards: image front and centre, clearer information, more visible selection.
• New FOV button: open the target's framing with your sensor in one tap.
• New polar trajectory chart with legend, also in the Sentinel project page.
• Colours by object type (nebulae, galaxies, clusters).