What Is FITS?
FITS (Flexible Image Transport System) is the standard data format in astronomy, endorsed by NASA and IAU. It stores both image data and precise metadata headers.
Windows Desktop Application
Turn FITS Data Into Stunning Astronomy Images
A professional FITS image visualization tool for Windows. Import astronomical survey data, apply intelligent stretch algorithms and color maps, and export wallpaper-quality images — all in seconds, fully offline.
Windows 10 / 11100% Offline7 LanguagesGPU Accelerated
In Action
From FITS Files to Beautiful Images
Astronomy's Snapseed — simple, instant feedback, visually driven. Complex parameters hidden in advanced options, zero-barrier default experience.
Batch FITS Import
Drag and drop multiple FITS files or entire folders. Parallel loading with real-time progress. Supports .fits, .fit, .fts extensions and multi-extension FITS files.
Auto Smart Enhance
One-click Auto button analyzes histogram shape and automatically selects the optimal stretch algorithm, color map, and black/white point combination.
Rich Color Maps
Choose from Viridis, Plasma, Inferno, Magma, Hubble Palette, and more. All perceptually uniform and colorblind-friendly with gradient preview swatches.
Live Histogram
Real-time 256-bin histogram visualization with black/white point markers. Drag sliders and see instant 200ms preview refresh — no waiting.
Beauty / Science Dual Mode
Beauty Mode hides scientific noise for clean images. Science Mode expands full analysis tools — beam overlay, pixel readout, PV diagrams, channel maps.
RGB Channel Synthesis
Assign R/G/B channels to different FITS images. Synthesize multi-band composite images with per-channel stretch and weight controls.
Wallpaper Export
Export to PNG/JPEG/FITS with preset resolutions from 1080p to 8K. Optional watermark with telescope model, observation band, and integration time.
Sky Info & Celestial Database
Auto-recognizes coordinates from WCS headers. Built-in offline database of 800+ celestial objects (Messier, NGC, IC) with Aitoff projection sky minimap.
FITS Header Viewer
Searchable three-column table (keyword/value/comment) for all FITS header entries. One-click value copy. Multi-extension support with extension switcher.
Science Tools
Moment maps, image algebra, position-velocity diagrams, channel maps for data cubes (NAXIS=3). Beam ellipse overlay from BMAJ/BMIN headers.
Undo / Redo
Full parameter undo/redo stack via Ctrl+Z / Ctrl+Y. Every adjustment is tracked and reversible. Non-destructive processing — original FITS data is never modified.
7-Language Localization
Full UI localization for English, Japanese, German, French, Spanish, Portuguese, and Russian. Switch languages at any time from Settings without restart.
Your Data Never Leaves Your Device
100% Offline
All FITS loading, stretch processing, and rendering runs locally. The app works fully offline after installation from the Microsoft Store.
Zero Data Upload
Your FITS files and rendered images are processed in memory on your own machine. No telemetry, no analytics, no data transmission of any kind.
No Account Needed
No sign-up, no login, no subscription. Download from the Microsoft Store and start exploring astronomical data immediately.
GPU Accelerated
Image rendering powered by SkiaSharp for fast, high-quality output. Optimized for large FITS files from modern astronomical surveys.
From Planning to Processing
Plan your observation session with FastTool's free browser tools, then bring your FITS data to life with AstroSky.
What Makes FITS Special
WCS Coordinates
World Coordinate System headers embedded in FITS files allow AstroSky to auto-detect sky position — no manual entry needed. Supports both Galactic and Equatorial frames.
Color Maps Matter
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Multi-Extension FITS
Modern telescopes store multi-wavelength data in a single .fits file with multiple extensions. AstroSky supports extension switching for seamless exploration.
Frequently Asked Questions
- Is AstroSky free?
- Yes. AstroSky is free to download from the Microsoft Store. No subscription, no in-app purchases, no account required.
- What Windows versions are supported?
- AstroSky runs on Windows 10 (version 1809+) and Windows 11. It is built with .NET 10 and WPF, with GPU acceleration via SkiaSharp.
- How is AstroSky different from the online FITS Viewer?
- The online FITS Viewer is for quick previews in your browser — instant, zero install. AstroSky is a full desktop application with intelligent auto-stretch, 12+ color maps, beauty/science dual mode, 8K export, WCS support, and GPU acceleration for large files.
- Does AstroSky require internet?
- No. After download and installation, AstroSky works 100% offline. All image processing happens on your local machine — no data ever leaves your device.
AstroSky is a Windows desktop application. All image processing runs locally on your device. No FITS data is ever uploaded to any server. The download link opens Microsoft Store in your default browser.
Plan Your Session with These Tools
Solar Insight Pro
Golden hour, sunrise, sunset, and UV index — plan when to shoot.
Sidereal Time Calculator
Calculate LST for precise telescope mount alignment.
Telescope FOV Calculator
Eyepiece field of view, magnification, and CCD sensor coverage.
Online FITS Viewer
Quick browser-based FITS preview — no download needed.
Already tried our free online FITS viewer? Go to FITS Viewer →