Knowledge base
Install & set up
Updated
How to install Nocturne, and how to connect the free tools it can use. You don’t need any of them to start, because Nocturne can run the whole process on its own. Two free downloads do make a real difference to the result, though.
Install Nocturne
Every release, for every platform, is on the downloads page. Nocturne is free and open source under the GPL; there is no account and no licence key.
macOS
For Apple Silicon Macs (M1 or newer); there is no Intel build. Download the zip, unpack it and drag Nocturne to Applications.
Nocturne isn’t notarized by Apple yet, so macOS refuses to open it the first time. Click Done, then go to System Settings → Privacy & Security, scroll down to Security, click Open Anyway and confirm with your password. You do this once for each new version.
Linux
For x86-64 PCs, as a tarball. There is no installer: unpack it anywhere and run the program inside:
tar -xzf Nocturne-<version>-linux-x86_64.tar.gz
./Nocturne/NocturneThe build host is Ubuntu 24.04, so it needs glibc 2.39 or newer.
That covers Ubuntu 24.04 and later, Debian 13, Fedora 40+ and current rolling distributions;
it will not start on Ubuntu 22.04. Check yours with ldd --version.
Tested on Xubuntu 24.04. Other desktops should work too, since Nocturne asks nothing unusual of the system.
Windows
Nocturne for Windows is an installer for 64-bit Windows 11, named Nocturne-<version>-windows-x64-setup.exe. It installs Nocturne for your user only, in %LOCALAPPDATA%\Programs\Nocturne, so it needs no administrator rights. It adds Nocturne to the Start menu and offers a desktop icon.
The installer isn’t signed yet, so Windows may show Windows protected your PC when you run it. Click More info, then Run anyway. Each new version is a new unsigned file, so the warning comes back with every update.
Once installed, double-clicking a .nocturne project opens it in Nocturne. FITS files (.fits, .fit, .fts) list Nocturne under Open with; the program they open with by default stays as it was.
To update, run the newer installer over the old one. To remove Nocturne, use Settings → Apps → Installed apps. Your settings and your images stay where they are.
Tested on Windows 11 Pro. Windows 10 has not been tried.
What happens on first launch
Nocturne looks in the usual install locations for the tools below and fills in any it finds, so on a typical computer there is nothing to configure. It also asks once whether it may send an anonymous daily usage count. Saying no changes nothing about how the app works. The privacy page explains exactly what is and isn’t sent.
The external tools
Some jobs are done by separate programs that Nocturne runs for you. You install them yourself, because their licences don’t allow Nocturne to include them, and connect each one in Settings.
If you install two things, make them GraXpert and StarNet2. Both are free, and they cover the two jobs where Nocturne’s built-in fallbacks are weakest: removing gradients and separating stars.
| Tool | Free or paid | What Nocturne uses it for | Without it |
|---|---|---|---|
| GraXpert | Free | Background extraction. Also one of the choices for noise reduction. | The Background step can’t run. Noise reduction uses Nocturne’s built-in engine. |
| StarNet2 | Free | Separating stars from the rest of the picture. Used by Star Reduction, De-green Stars, Nebula Saturation, Narrowband, Starless Levels, Star Colour, Sharpen Nebulosity, Upscale Crop and Colour Balance. | Nocturne’s own separator, which leaves about twice as much starlight behind. |
| ASTAP | Free | Plate solving, with the D05 star database: identifying the target, annotation, photometric colour calibration and mosaic stacking. | No plate solving and no mosaics. Colour balances on the sky instead. |
| StarXTerminator | Paid (RC-Astro) | Star separation. Nocturne prefers it over StarNet2 when both are installed. Also the starless + stars export. | StarNet2, or the built-in separator. Both make the starless + stars export too. |
| NoiseXTerminator | Paid (RC-Astro) | Noise reduction. | GraXpert, or the built-in engine. |
| BlurXTerminator | Paid (RC-Astro) | Deconvolution, which sharpens stars and fine detail. | Nocturne’s built-in sharpening. |
Auto Enhance uses whichever of these you have installed.
GraXpert free
Free and open source (GPL-3.0). Nocturne uses it for background extraction, removing gradients, light-pollution glow and vignetting, and as one of its denoise engines.
- Download from graxpert.com.
- macOS — the .app, Apple Silicon or Intel. Drag it to Applications and Nocturne finds it on its own.
- Linux — a zip containing a folder with a
GraXpertexecutable at the top; there is no installer, so wherever you unpack it is the install. Unpack it to~/Applications/GraXpert-linux/and Nocturne finds it; an AppImage in~/Applications/works too. - Windows — run the installer. Nocturne finds GraXpert in
%LOCALAPPDATA%\Programs\GraXpertorC:\Program Files\GraXpert.
StarNet2 free
Separates an image into a starless picture and a stars layer. More of Nocturne depends on this than on anything else on this page: Star Reduction, De-green Stars, Nebula Saturation, Narrowband, Starless Levels, Star Colour, Sharpen Nebulosity, Upscale Crop, Auto Enhance and Colour Balance all use it.
Without it, those steps use Nocturne’s own separator. It works, but leaves about twice as much starlight behind, which shows as grey blobs where the bright stars were. StarNet2 is free, so it is well worth installing.
- Download from the StarNet CLI tools page. Take the CLI package. The PixInsight module on the same site is a different product, and Nocturne can’t use it.
- macOS — the
.pkginstaller is easiest and puts it in/usr/local/bin. The portable zip works too; unpack it under~/Applications/and keep the executable and its weights folder together. - Linux — the
.deb(sudo apt install ./StarNet2_linux_*.deb), or the CLI zip unpacked to~/Applications/. - Windows — Nocturne finds it in
C:\Program Files\StarNet2\. If you unpacked it somewhere else, point atstarnet2.exein Settings.
StarNet2 can’t come with Nocturne, because its licence doesn’t allow it to be passed on. It is free to download and free to use.
ASTAP free optional
A free plate solver. It works out exactly where a frame points, which unlocks target identification, annotation (object labels, compass, scale bar), photometric colour calibration and mosaic stacking.
- Download from the ASTAP page —
a macOS build, a Linux
.deband a Windows installer, which puts it inC:\Program Files\astap. - You also need a star database. On the same page, download D05 and install it as described there; it suits a smart telescope’s field of view. Without a star database, ASTAP can’t solve anything.
- In Nocturne, open Settings → ASTAP and press Test to confirm it's found.
RC-Astro optional · paid
Russell Croman’s BlurXTerminator (deconvolution and sharpening), NoiseXTerminator (denoise) and StarXTerminator (star removal). Nocturne uses them when they are installed. Every step that can use RC-Astro also works without it: StarNet2 does StarXTerminator’s job, and Nocturne’s own code does the rest.
- Purchase and download from rc-astro.com (one-time purchase; macOS, Linux and Windows builds; see the site for current pricing).
- Nocturne uses the standalone versions, so you don’t need PixInsight or Photoshop. Set the path in Settings, and choose your denoise engine there too.
- On Windows, Nocturne looks in
C:\Program Files\RC-Astro\CLI\and%LOCALAPPDATA%\Programs\RC-Astro\CLI\. Those places have not been checked on a real RC-Astro install for Windows yet, so if Nocturne does not find it, point atrc-astro.exein Settings with Browse….
Pointing Nocturne at them
Open Settings. Each tool has a row with its path, a Browse… button, a Test button that actually runs the tool, and a Download ↗ link if you haven't got it yet.
Rescan for installed apps checks the standard locations again. It only fills in rows that are empty or broken, and never replaces a path you set yourself.
These are the places Nocturne looks on its own:
| Tool | macOS | Linux |
|---|---|---|
| GraXpert | /Applications/GraXpert.app |
~/Applications/GraXpert-linux/GraXpert, /opt/GraXpert*, an AppImage, or PATH |
| StarNet2 | /usr/local/bin/starnet2, ~/Applications/starnet2*/ |
/usr/bin/starnet2, ~/Applications/starnet2*/, or PATH |
| ASTAP | /Applications/ASTAP.app, /opt/homebrew/bin/astap |
/usr/bin/astap, /opt/astap/astap, or PATH |
| RC-Astro | /Applications/RC-Astro/CLI/rc-astro |
/opt/RC-Astro/CLI/rc-astro, ~/Applications/RC-Astro/CLI/rc-astro |
| Tool | Windows |
|---|---|
| GraXpert | %LOCALAPPDATA%\Programs\GraXpert\GraXpert.exe, C:\Program Files\GraXpert\GraXpert.exe, or PATH |
| StarNet2 | C:\Program Files\StarNet2\bin\starnet2.exe, C:\Program Files\StarNet2\starnet2.exe, %LOCALAPPDATA%\Programs\StarNet2\bin\starnet2.exe, or PATH |
| ASTAP | C:\Program Files\astap\astap.exe, C:\Program Files (x86)\astap\astap.exe, C:\astap\astap.exe, or PATH |
| RC-Astro | C:\Program Files\RC-Astro\CLI\rc-astro.exe, %LOCALAPPDATA%\Programs\RC-Astro\CLI\rc-astro.exe, or PATH. Not yet checked on a real install; if it is not found, use Browse… |
A tool installed anywhere else works too: point at it with Browse…. This list is only where Nocturne looks on its own.
If something isn't found
“Set, but cannot be run.” The path points at something that isn't
executable. On Linux that is usually a missing execute bit after unpacking:
chmod +x the binary. On macOS it can be quarantine — open the tool once from
Finder and allow it. On Windows, the path has to name the .exe
itself, not its folder.
Installed, but Rescan doesn’t see it. Point at it with Browse… and Nocturne remembers it. If the tool is somewhere common that Nocturne misses, say so and that place will be added to the list.
A step seems to do nothing. Without StarNet2 or RC-Astro, the star-based steps use the built-in separator, and on a picture with few stars the difference can be hard to see. Settings shows which engine is in use, and the provenance report records it for every step you ran.
GraXpert or StarNet2 runs but takes a long time. Both run a neural network over the full-resolution picture. Ten to sixty seconds is normal; Nocturne shows progress, and you can cancel at any time.
Still stuck? The FAQ covers the common ones, and issues go on GitHub.
All set? The guide explains what each step does, and how to choose between the options it offers.