AstroPlanner

A horizon-aware deep sky object planner for visual observers and astrophotographers.

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Screenshots

Horizon-aware object list with visibility scores


Object detail — altitude plot, moon info, and imaging log


Interactive FOV preview on real DSS imagery


Yearly best-time heatmap

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What it does

AstroPlanner tells you what's worth observing tonight and exactly how long you have to observe it. It loads the full NGC/IC/Messier/Caldwell catalog, computes each object's altitude throughout the night against your custom horizon profile, and scores every object based on how long it clears your horizon and your local sky conditions. Point it at a night, pick your location, and it hands you a ranked list you can actually trust.

Features

Planning

• Horizon-aware visibility — import a custom horizon profile (azimuth/altitude pairs) so the app knows about your tree line, rooftop, or observatory walls
• Visibility scoring — each object is scored by how long it clears your horizon at a useful altitude, weighted by sky quality
• Yearly best-time view — month-by-month heatmap showing the best observing windows for any object across the entire year
• Observation date picker — plan ahead for any night, not just tonight

Catalog

• NGC, IC, Messier, and Caldwell objects from the embedded OpenNGC catalog
• Solar system objects — planets and the Moon with live positional data
• Comet tracking — fetches current bright comet data with real-time ephemerides
• Filters — narrow by object type (galaxies, nebulae, clusters, planets, comets), favorites, or visible-only

Telescope & FOV

• Imaging setup manager — define multiple telescope + camera combinations with focal length, sensor size, and pixel scale
• FOV Preview — interactive sky view powered by Aladin Lite with your FOV overlaid on real DSS imagery, rotatable to match your camera angle
• Best setup suggestion — automatically highlights the setup whose FOV best fits the target object

Site & Sky

• Multiple observation locations — save and switch between sites with one click
• Light pollution lookup — fetches your Bortle class automatically from lightpollutionmap.info
• Weather integration — hourly cloud cover, transparency, seeing, and wind from Open-Meteo and 7timer ASTRO

Object detail

• Altitude plot — full-night arc showing rise, transit, and set against your horizon
• Moon interference — moon phase and separation angle for the selected object
• Favorites & imaging log — mark objects as favorites or log the date you imaged them
• Open in Stellarium — one click sends the object to Stellarium's telescope view
• AstroBin — opens the object's AstroBin search page for reference images

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Download

Grab the latest build from the Releases page.

Platform	File	Notes
Windows	AstroPlanner-x.x-Setup.exe	Installs to Program Files, adds Start Menu & desktop shortcuts
macOS	AstroPlanner-x.x-macos.tar.gz	Extract and run AstroPlanner.app. Right-click → Open on first launch to bypass Gatekeeper
Linux	AstroPlanner-x86_64.AppImage	chmod +x AstroPlanner-x86_64.AppImage then run

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Built with

Language	C# / .NET 10
UI framework	Avalonia UI — native cross-platform desktop
Astronomy math	AASharp — port of Jean Meeus' Astronomical Algorithms
Sky viewer	Aladin Lite v3 embedded via WebView
Catalog	OpenNGC by Mattia Verga (bundled, CC BY-SA 4.0)
Object images	NASA SkyView (DSS2) + DESI Legacy Survey DR10
Comet data	Minor Planet Center (IAU)
Weather	Open-Meteo + 7timer ASTRO
Light pollution	lightpollutionmap.info
CSV parsing	CsvHelper by Josh Close
MVVM	CommunityToolkit.Mvvm

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Building from source

Requires the .NET 10 SDK.

git clone https://github.com/tankhardrive/AstroPlanner.git
cd AstroPlanner
dotnet run --project AstroPlanner/AstroPlanner.csproj

To publish for a specific platform:

dotnet publish AstroPlanner/AstroPlanner.csproj -c Release -r win-x64 --self-contained
dotnet publish AstroPlanner/AstroPlanner.csproj -c Release -r osx-x64 --self-contained
dotnet publish AstroPlanner/AstroPlanner.csproj -c Release -r linux-x64 --self-contained

Installer scripts are in the repo root (installer.nsi for Windows, build-macos.sh for macOS).

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Credits

Built by tankhardrive with the help of Claude Code by Anthropic.

Third-party data

The bundled NGC/IC catalog (AstroPlanner/Assets/Data/NGC.csv) is OpenNGC, created by Mattia Verga and contributors, and licensed under CC BY-SA 4.0. This data is not covered by the MIT license that applies to the AstroPlanner source code. See NOTICES for full attribution details.